Deriving the operational procedure for the Universal Thermal Climate Index (UTCI)

The Universal Thermal Climate Index (UTCI) aimed for a one-dimensional quantity adequately reflecting the human physiological reaction to the multi-dimensionally defined actual outdoor thermal environment. The human reaction was simulated by the UTCI-Fiala multi-node model of human thermoregulation, which was integrated with an adaptive clothing model. Following the concept of an equivalent temperature, UTCI for a given combination of wind speed, radiation, humidity and air temperature was defined as the air temperature of the reference environment, which according to the model produces an equivalent dynamic physiological response. Operationalising this concept involved (1) the definition of a reference environment with 50% relative humidity (but vapour pressure capped at 20 hPa), with calm air and radiant temperature equalling air temperature and (2) the development of a one-dimensional representation of the multivariate model output at different exposure times. The latter was achieved by principal component analyses showing that the linear combination of 7 parameters of thermophysiological strain (core, mean and facial skin temperatures, sweat production, skin wettedness, skin blood flow, shivering) after 30 and 120 min exposure time accounted for two-thirds of the total variation in the multi-dimensional dynamic physiological response. The operational procedure was completed by a scale categorising UTCI equivalent temperature values in terms of thermal stress, and by providing simplified routines for fast but sufficiently accurate calculation, which included look-up tables of pre-calculated UTCI values for a grid of all relevant combinations of climate parameters and polynomial regression equations predicting UTCI over the same grid. The analyses of the sensitivity of UTCI to humidity, radiation and wind speed showed plausible reactions in the heat as well as in the cold, and indicate that UTCI may in this regard be universally useable in the major areas of research and application in human biometeorology.     

Comparison of UTCI to selected thermal indices

Over the past century more than 100 indices have been developed and used to assess bioclimatic conditions for human beings. The majority of these indices are used sporadically or for specific purposes. Some are based on generalized results of measurements (wind chill, cooling power, wet bulb temperature) and some on the empirically observed reactions of the human body to thermal stress (physiological strain, effective temperature). Those indices that are based on human heat balance considerations are referred to as "rational indices". Several simple human heat balance models are known and are used in research and practice. This paper presents a comparative analysis of the newly developed Universal Thermal Climate Index (UTCI), and some of the more prevalent thermal indices. The analysis is based on three groups of data: global data-set, synoptic datasets from Europe, and local scale data from special measurement campaigns of COST Action 730. We found the present indices to express bioclimatic conditions reasonably only under specific meteorological situations, while the UTCI represents specific climates, weather, and locations much better. Furthermore, similar to the human body, the UTCI is very sensitive to changes in ambient stimuli: temperature, solar radiation, wind and humidity. UTCI depicts temporal variability of thermal conditions better than other indices. The UTCI scale is able to express even slight differences in the intensity of meteorological stimuli.     

Effect of soil temperature and moisture on survival of eggs and first-instar larvae of Delia radicum

Edaphic factors such as soil temperature and moisture influence soil-dwelling insects, whose most vulnerable stages typically are eggs and young larvae. In this study, the survival of eggs and first-instar larvae of the cabbage maggot, Delia radicum L., was measured under laboratory conditions after exposure to a range of soil temperatures and moistures. When eggs were exposed to constant temperature (20-29°C) and humidity (5-200% [wt:wt]), temperature had no significant effect on survival, whereas humidity <25% [wt:wt] caused egg mortality. The gradual exposure of eggs to high temperatures resulted in low mortality below 33°C, but <5% of eggs survived at 40°C. When first-instar larvae were exposed to constant temperature (17-29°C) and humidity (5-100% [wt:wt]), both factors as well as their interaction had a significant effect on larval survival, which was nil at 5% (wt:wt) for all temperatures but increased from 21.9 to 42.8% at 17°C and from 34.1 to 55.0% at 29°C, for soil moisture contents of 15% and 100% (wt:wt), respectively. Eggs of D. radicum are resistant to low soil moisture and high temperature conditions. Larval survival tends to increase with an increase in soil temperature and moisture. It is suggested that soil temperature be integrated into insect development simulation models instead of air temperature, to build more effective models for cabbage maggot management.     

UTCI—Why another thermal index?

Existing procedures for the assessment of the thermal environment in the fields of public weather services, public health systems, precautionary planning, urban design, tourism and recreation and climate impact research exhibit significant shortcomings. This is most evident for simple (mostly two-parameter) indices, when comparing them to complete heat budget models developed since the 1960s. ISB Commission 6 took up the idea of developing a Universal Thermal Climate Index (UTCI) based on the most advanced multi-node model of thermoregulation representing progress in science within the last three to four decades, both in thermo-physiological and heat exchange theory. Creating the essential research synergies for the development of UTCI required pooling the resources of multidisciplinary experts in the fields of thermal physiology, mathematical modelling, occupational medicine, meteorological data handling (in particular radiation modelling) and application development in a network. It was possible to extend the expertise of ISB Commission 6 substantially by COST (a European programme promoting Cooperation in Science and Technology) Action 730 so that finally over 45 scientists from 23 countries (Australia, Canada, Israel, several Europe countries, New Zealand, and the United States) worked together. The work was performed under the umbrella of the WMO Commission on Climatology (CCl). After extensive evaluations, Fiala’s multi-node human physiology and thermal comfort model (FPC) was adopted for this study. The model was validated extensively, applying as yet unused data from other research groups, and extended for the purposes of the project. This model was coupled with a state-of-the-art clothing model taking into consideration behavioural adaptation of clothing insulation by the general urban population in response to actual environmental temperature. UTCI was then derived conceptually as an equivalent temperature (ET). Thus, for any combination of air temperature, wind, radiation, and humidity (stress), UTCI is defined as the isothermal air temperature of the reference condition that would elicit the same dynamic response (strain) of the physiological model. As UTCI is based on contemporary science its use will standardise applications in the major fields of human biometeorology, thus making research results comparable and physiologically relevant.     

气候舒适度在不同海拔的时空变化特征及其影响因素

气候舒适度是在气候变化背景下评估热量变化的方式之一.本研究基于1984-2013年间贵州省84个气象台站的逐日观测数据,采用通用热气候指数(UTCI)讨论不同海拔的气候舒适度时空变化规律及主要影响因子,定量分析了不同海拔地区各气候因子对UTCI的影响差异.结果表明: 1984-2013年间,贵州省多年平均UTCI与气温在空间分布格局上有很强的一致性,均表现为温度随海拔升高而降低,全省大部分地区年舒适天数在180～240 d之间;贵州省各站点UTCI增幅随海拔升高而增大,且UTCI变化幅度[-0.58～1.38 ℃·(10 a)^-1]高于气温变化幅度[-0.36～0.45 ℃·(10 a)^-1];在全省范围内,UTCI与各气候因子的相关关系由大至小依次为气温、风速、气压、相对湿度和云量,相关系数分别为0.899、-0.855、0.818、-0.373和-0.042;在不同海拔地区,不同因子与UTCI的相关系数变化有很大的不一致性.随海拔升高,UTCI受气温影响逐渐减弱,风速的影响程度增大.     

Too hot for comfort: The heatwaves in Greece in 1987 and 1988

The heatwaves that affected Greece in July 1987 and July 1988 are considered in terms of (i) the relative strain index. For different types of activity, and (ii) the discomfort index. Hourly values of air temperature and humidity for Thessaloniki and Athens were used as the data base. Both indices show that in terms of physiological strain and general discomfort, Thessaloniki suffered a little more and a little longer than Athens. We conclude that the relative strain index is probably a useful tool in studies of the adverse effects of humid heatwaves on different sections of a population.     

Human tolerance to heat strain during exercise: influence of hydration.

This study determined whether 1) exhaustion from heat strain occurs at the same body temperatures during exercise in the heat when subjects are euhydrated as when they are hypohydrated, 2) aerobic fitness influences the body temperature at which exhaustion from heat strain occurs, and 3) curves could be developed to estimate exhaustion rates at a given level of physiological strain. Seventeen heat-acclimated men [maximal oxygen uptake (VO2max) from 45 to 65 ml.kg-1.min-1] attempted two heat stress tests (HSTs): one when euhydrated and one when hypohydrated by 8% of total body water. The HSTs consisted of 180 min of rest and treadmill walking (45% VO2max) in a hot-dry (ambient temperature 49 degrees C, relative humidity 20%) environment. The required evaporative cooling (Ereq) exceeded the maximal evaporative cooling capacity of the environment (Emax); thus thermal equilibrium could not be achieved and 27 of 34 HSTs ended by exhaustion from heat strain. Our findings concerning exhaustion from heat strain are 1) hypohydration reduced the core temperature that could be tolerated; 2) aerobic fitness, per se, did not influence the magnitude of heat strain that could be tolerated; 3) curves can be developed to estimate exhaustion rates for a given level of physiological strain; and 4) exhaustion was rarely associated with a core temperature up to 38 degrees C, and it always occurred before a temperature of 40 degrees C was achieved. These findings are applicable to heat-acclimated individuals performing moderate-intensity exercise under conditions where Ereq approximates or exceeds Emax and who have high skin temperatures.     

Using a priori contrasts for multivariate repeated-measures ANOVA to analyze thermoregulatory responses of the dibbler (Parantechinus apicalis; Marsupialia, Dasyuridae)

Physiological studies often involve the repeated measurement of individuals over a range of ordered categorical conditions, for example, varying ambient temperature. We illustrate here the use of a priori contrasts for multivariate repeated-measures ANOVA by analyzing the thermal responses of various physiological variables for a small marsupial, the dibbler (Parantechinus apicalis). Our analyses showed that dibblers conform closely to the Scholander-Irving model of endothermy. Body temperature was constant at low air temperatures, was 36.3 ± 0.24°C at thermoneutrality (30°C), and increased at 35°C. Metabolic rate decreased with increasing ambient temperature to a basal rate of 0.619 ± 0.036 mL O(2) g(-1) h(-1) at 30°C; it extrapolated closely to thermoneutral body temperature. Increased oxygen demand at lower ambient temperature was met by increased respiratory minute volume, achieved by increased respiratory frequency and tidal volume; oxygen extraction was constant at about 19%. Evaporative water loss and wet and dry thermal conductance increased markedly at high ambient temperatures but not sufficiently to maintain constant body temperature. Relative water economy was similar to that of other small marsupials, increasing linearly at lower air temperatures with a point of relative water economy of 20.3°C. We conclude that a priori contrasts provide a statistically appropriate and powerful analysis that can be used routinely to statistically describe the pattern of response of physiological variables to a categorical factor and are especially useful for repeated-measures ANOVA designs common to many physiological studies.     

Applications of real-time thermoregulatory models to occupational heat stress: validation with military and civilian field studies

A real-time thermoregulatory model using noninvasive measurements as inputs was developed for predicting physiological responses of individuals working long hours. The purpose of the model is to reduce heat-related injuries and illness by predicting the physiological effects of thermal stress on individuals while working. The model was originally validated mainly by using data from controlled laboratory studies. This study expands the validation of the model with field data from 26 test volunteers, including US Marines, Australian soldiers, and US wildland fire fighters (WLFF). These data encompass a range of environmental conditions (air temperature: 19-30° C; relative humidity: 25-63%) and clothing (i.e., battle dress uniform, chemical-biological protective garment, WLFF protective gear), while performing diverse activities (e.g., marksmanship, marching, extinguishing fires, and digging). The predicted core temperatures (Tc), calculated using environmental, anthropometric, clothing, and heart rate measures collected in the field as model inputs, were compared with subjects' Tc collected with ingested telemetry temperature pills. Root mean standard deviation (RMSD) values, used for goodness of fit comparisons, indicated that overall, the model predictions were in close agreement with the measured values (grand mean of RMSD: 0.15-0.38° C). Although the field data showed more individual variability in the physiological data relative to more controlled laboratory studies, this study showed that the performance of the model was adequate.     

Effect of temperature and relative humidity on the development and fecundity of Chilo partellus (Swinhoe) (Lepidoptera: Crambidae)

The spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), is one of the most important insect pests attacking maize and sorghum in Ethiopia. Recent studies have indicated that the pest is spreading to new locations where it was not reported before. In the current study, laboratory investigations were carried out to determine the combined effect of different levels of relative humidity and temperature regimes on the development and fecundity of C. partellus, as these physical factors are known to play an important role in the life cycle of insects and adaptability to local climate. Developmental time, longevity, potential fecundity and realized fecundity of C. partellus were measured under controlled conditions. Three temperature regimes (22°C, 26°C and 30°C) and three relative humidity levels (40%, 60% and 80%) were tested. It was found that temperature, relative humidity (RH) and their interaction significantly affected the developmental time, adult longevity, potential fecundity and realized fecundity of the pest. Developmental time was inversely related to temperature. Mean duration of C. partellus life cycle was 70.2 days at 22°C and 80% RH, whereas it took only 26.5 days to complete its life cycle at 30°C and 40% RH. Male and female longevity were similar in most cases. The adult life span ranged between 6.9-11.1 days at 22°C and 3.1-7.2 days at 30°C for different levels of relative humidity. The most suitable conditions for C. partellus development and fecundity were 26-30°C temperatures regimes and 60-80% RH levels.     

Influence of climatic conditions on the mutations in pollen mother cells of Tradescantia clone 4430 and implications for the Trad-MCN bioassay protocol

The present was study aimed at investigating the influence of relative humidity and temperature on spontaneous and pollution-induced mutation rates during exposure and recovery periods in the Trad-MCN test. Cuttings of Tradescantia clone 4430 were exposed to a negative control, to 4 mM maleic hydrazide (MH), and to a polluted water sample under varying conditions of air temperature and humidity in climatic chamber experiments. The relative humidity did not affect the spontaneous mutation rate in the clone investigated, but was negatively correlated with the frequency of pollution-induced mutations. Low temperature caused an increase in the number of micronuclei in the negative control, but no comparable response in polluted samples. At an extremely high temperature, signs of strong physiological damage and/or of a meiotic delay of pollen maturation were detected. When the temperature increased gradually and the extreme value was maintained only for short time, such detrimental effects were not observed. Subsequent treatment with high and low temperatures, by contrast, resulted in the highest MCN rates of all experiments. Our studies point to the possibility of producing irregular results of the Trad-MCN test if the influence of climatic factors has not sufficiently been considered.     

Use of physiological parameters to predict milk yield and feed intake in heat-stressed dairy cows

Holstein cows were tested to determine which measures of thermal strain are the better predictors of production over 24–96 h at constant air temperatures of 19 and 29 °C. Both rectal temperature and respiration rate increased within 24 h, followed by milk yield and feed intake reductions after 48 h of heat stress. There were significant correlations between milk yield, feed intake, and rectal temperature. Several physiological strain indices were created to determine if combinations of measures are better than single measures in predicting production under these acute conditions. Mean daily rectal temperature was superior to maximum and minimum daily values of rectal temperature, as well as other indicators of thermal status in predicting dairy cow production. Likewise, mean daily rectal temperature was equal if not better than the physiological strain indices used in this study in predicting production. These data suggest that rectal temperature is superior to both single and combined indicators of thermal status in predicting dairy cow production, and should be considered for future development of physiological strain indices over a longer time period in both laboratory and field environments.     

Aeroterrestrial Microalgae Growing in Biofilms on Facades—Response to Temperature and Water Stress

The photosynthetic performance of a microalgal biofilm colonizing a building facade was investigated between February and July 2004, with an emphasis on changing water availability and air humidity. The fluorimetric measurements of the quantum efficiency (F _v/F _m) indicated diurnal activity patterns. At most sampling dates the algal biofilm photosynthesized particularly in the morning and substantially less in the afternoon. As long as liquid water was present, the microalgae exhibited at least some degree of photosynthesis. However, F _v/F _m values never exceeded 0.4, pointing to slight photoinhibition or damage of the cells. Dried cells without photosynthesis could recover within minutes after artificial moistening.Three microalgal strains were isolated from aeroterrestrial biofilms and established as unialgal cultures. Their photosynthesis and growth were characterized under different air humidities and temperatures. Photosynthesis and growth of strain ROS 55/3 (Stichococcus sp.) showed similar patterns with decreasing relative air humidity. Positive growth and optimum photosynthesis were recorded at 100% relative air humidity. At air humidities below 93%, both processes were strongly inhibited. All studied strains grew between 1 and 30°C with optimum rates at 20–23°C, indicating eurythermal features.The data indicate that liquid water or 100% air humidity are the prerequisite for optimum photosynthesis and growth of aeroterrestrial microalgae. However, when dried and consequently inactive, these microorganisms can recover quickly if water is suddenly available, e.g., after rain events. These physiological capabilities explain well the ecological success of aeroterrestrial microalgae in occupying many man-made substrata such as building facades and roof tiles in urban areas.     

Combined Influence of Intermittent Exercise and Temperature Stress on the Modulation of Fluoride Toxicity

Regardless of the circumstantial evidences on the involvement of fluoride on the etiology and pathogenesis of fluorosis, several lines of evidences strongly indicate the influence of modulator factors such as duration of fluoride exposure, age, temperature, and physical activity. This study has been designed to investigate the combined influence of intermittent exercise and temperature stress on the modulation of fluoride toxicity. Three-month-old Wistar male rats were exposed to high sodium fluoride (600 ppm) through drinking water for 1 month and the rats were then subjected to swimming exercise at different temperatures (20°C, 25°C, 30°C, and 35°C). Oxidative stress indices analyzed showed fluoride-induced oxidative stress in biological tissues studied like brain, heart, liver, and kidney. Exercise regimen coupled with different temperatures were found to be effective in bringing the oxidative stress indices to near normal level indicating decreased free radical production which may be a compensatory mechanism to counteract against the detrimental effects of fluoride. Further, the deleterious effects of fluoride significantly reduced at 25°C and 30°C demonstrating that the thermoneutral temperatures were effective in reducing the toxicity level.     

Effects of temperature and relative humidity on mating and survival of sterile Drosophila suzukii

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a widely distributed pest species of soft-skinned fruits. Recent studies suggest the use of sterile insect technique (SIT) as a control method for this species; however, many factors can impact effectiveness of a SIT programme, including the environmental conditions. Environmental condition is critical at the time of the release and in the days afterwards, since it may impact sterile insects’ survival and ability to mate. Thus, we verified the influence of temperature and relative humidity on mating and survival of fertile and sterile D. suzukii, when insects were food provided or deprived. Highest mating rates occurred when sterile or fertile flies provided with food were exposed to 25ºC or 81%–100% relative humidity, while temperatures of 10 and 35ºC and humidity below 60% impaired mating. Overall, mating rate among food-deprived flies was low in all temperatures and humidity levels tested, but fertile insects were more prone to mate when compared to sterile flies. Survival was negatively influenced by high temperatures, low relative humidity and food deprivation. The information present in this study is useful to be considered for release of sterile D. suzukii.     

Can we improve heterosis for root growth of maize by selecting parental inbred lines with different temperature behaviour?

Tolerance to high and low temperature is an important breeding aim for Central and Northern Europe, where temperature fluctuations are predicted to increase. However, the extent to which genotypes differ in their response to the whole range of possible temperatures is not well understood. We tested the hypothesis that the combination of maize (Zea mays L.) inbred lines with differing temperature optima for root growth would lead to superior hybrids. This hypothesis is based on the concept of 'marginal overdominance' in which the hybrid expresses higher relative fitness than its parents, summed over all situations. The elongation rates of axile and lateral roots of the reciprocal cross between two flint and two dent inbred lines were assessed at temperatures between 15°C and 40°C. Indeed, the cross between UH005 and UH250 with lateral root growth temperature optima at 34°C and 28°C, respectively, resulted in intermediate hybrids. At temperatures below and above 31°C, the hybrids' root growth was comparable to the better parent, respectively, thereby increasing temperature tolerance of the hybrid compared with its parents. The implications of and reasons for this heterosis effect are discussed in the context of breeding for abiotic stress tolerance and of putatively underlying molecular mechanisms. This finding paves the way for more detailed investigations of this phenomenon in future studies.     

Comparisons of urban and rural bioclimatological conditions in the case of a Central-European city

This paper examines the influence of a medium-sized city (Szeged, Hungary) on the bioclimatological conditions of human beings. With the help of suitable indices for the available data set, differences in the annual and diurnal variation of human bioclimatic characteristics between an urban and rural environment are evaluated over a 3-year period. These indices are the thermohygrometric index (THI, defined by air temperature and relative humidity), the relative strain index (RSI, defined by air temperature and vapour pressure) and the number of ”beergarden days” (defined by air temperature at 2100 hours). In urban and rural areas, ”hot” THI conditions characterize 6% and 1% of the year, ”comfortable” conditions 30% and 20%, ”cool” conditions 10% and 12%, and ”cold” conditions 54% and 66% respectively. Over longer periods (e.g. one, month) RSI remains below the threshold value for strong heat stress in the city. The monthly frequencies of beergarden days show that these days appears from May until October and the city has almost twice as many pleasant evenings as the rural areas. Consequently, the city favourably modifies the main climatological elements within the general climate of its region; periods likely to be comfortable are therefore found more frequently in the city than in rural areas. Received: 24 November 1998 / Revised: 14 June 1999 / Accepted: 4 August 1999     

Estimation of feeding threshold for Homalodisca vitripennis (Hemiptera: Cicadellidae) and its application to prediction of overwintering mortality

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar), vectors the bacterium Xylella fastidiosa that induces Pierce's disease of grape. This study determined the effect of temperature on the feeding activity of H. vitripennis adults and the resulting production of excreta. The Logan type I model described a nonlinear pattern that showed excreta production increased up to an optimal temperature (33.1°C), followed by an abrupt decline near an estimated upper threshold (36.4°C). A temperature threshold for feeding, at or below which adults cease feeding, was estimated to be 10°C using a linear regression model based on the percentage of adults producing excreta over a range of constant temperatures. A simulated winter-temperature experiment using fluctuating thermal cycles confirmed that a time period above the temperature threshold for feeding was a critical factor in determining adult survival. Using data from the simulated temperature study, a predictive model was constructed by quantifying the relationship between cumulative mortality and cooling degree-hours. In field validation experiments, the model accurately predicted the temporal pattern of overwintering mortality of H. vitripennis adults held under winter temperatures simulating conditions in Bakersfield and Riverside, California, in 2006-2007. Model prediction using winter temperature data from a Riverside weather station indicated that H. vitripennis adults would experience an average of 92% overwintering mortality before reproduction in the spring, but levels of mortality varied depending on winter temperatures. The potential for temperature-based indices to predict temporal and spatial dynamics of H. vitripennis overwintering is discussed.     

苹果果面日最高温与主要气象因子的关系

一天中 ,苹果果实表面最高温度与气温、日照、相对湿度和风速有着密切的关系。通过生长季自动监测果实表面温度的变化 ,并与设置在监测树旁边气象记录仪数据对比 ,揭示出树冠西南部果实表面温度与气温、日照、相对湿度和风速呈高度相关。结果还表明 :日照和气温是导致果实表面高温 (>45℃ )的两个主要因子。在大多数情况下 ,这两个因子相互作用决定果实高温是否发生 ,但气温的作用更为重要。一般在晴天 ,树冠西南部果实表面高温通常出现在 1 3 :3 0～ 1 5 :5 0。果实达到临界日烧高温 (>45℃ )的综合气象条件是 (1 0 :0 0～ 1 6 :0 0平均值 ) :日照 >5 80 W/m2 ;气温 >3 1 .8℃ ;风速 <1 .0 m/s;相对湿度 <3 0 %。气温、日照、风速和相对湿度与果实表面温度都呈高度相关 ,其多元回归方程为 :果实表面温度 (℃ ) =1 9.7 0 .842×气温 (℃ ) 0 .0 0 989×日照 (W/m2 ) - 2 .0 8×风速 (m/s) - 0 .1 48×相对湿度 (% ) ,r2 =0 .6 97     

Climate change and thermal comfort in Hong Kong

Thermal comfort is a major issue in cities and it is expected to change in the future due to the changing climate. The objective of this paper is to use the universal thermal comfort index (UTCI) to compare the outdoor thermal comfort in Hong Kong in the past (1971–2000) and the future (2046–2065 and 2081–2100). The future climate of Hong Kong was determined by the general circulation model (GCM) simulations of future climate scenarios (A1B and B1) established by the Intergovernmental Panel on Climate Change (IPCC). Three GCMs were chosen, GISS-ER, GFDL-CM2.1 and MRI-CGCM2.3.2, based on their performance in simulating past climate. Through a statistical downscaling procedure, the future climatic variables were transferred to the local scale. The UTCI is calculated by four predicted climate variables: air temperature, wind speed, relative humidity and solar radiation. After a normalisation procedure, future UTCI profiles for the urban area of Hong Kong were created. Comparing the past UTCI (calculated by observation data) and future UTCI, all three GCMs predicted that the future climate scenarios have a higher mode and a higher maximum value. There is a shift from ‘No Thermal Stress’ toward ‘Moderate Heat Stress’ and ‘Strong Heat Stress’ during the period 2046–2065, becoming more severe for the later period (2081–2100). Comparing the two scenarios, B1 exhibited similar projections in the two time periods whereas for A1B there was a significant difference, with both the mode and maximum increasing by 2 °C from 2046–2065 to 2081–2100.