In a survey of 170 elementary students in the Phoenix, AZ metropolitan area over August-September 2024 (average maximum temperature during this period was 97°F), students reported feeling "a lot hot" directly after recess in 45% of surveys—and higher perceived heat was associated with greater physical activity intensity, according to a study published November 11, 2026 in the open access journal PLOS Global Public Health by Kylie Wilson from University of Arizona Cancer Center, United States, and colleagues.
Extreme heat can impact how and if children play outside while at school. Children younger than 10 may be uniquely vulnerable to heat-related illness during extreme temperatures for both physiological and behavioral reasons.. In this study, the authors examined if children's perceptions of heat while playing outside corresponded with actual air temperatures, as well as whether their perceptions of outdoor heat were related to changes in their recess activity over time.
Wilson and colleagues surveyed children at five elementary schools in the Phoenix Metropolitan Region (Arizona, United States) during the first six weeks of the 2024-2025 school year (August-September). During this period, Phoenix experienced extreme heat: its hottest September, its hottest year (2024) to date, and the longest run of days with maximum temperatures at or above 100°F (37.8°C). Across the four schools included in analyses, average outdoor shade canopy coverage ranged from 13.5% to 53.9%.
Immediately after outdoor lunch recess, students self-reported the intensity of their physical activity on a 3-point scale: sedentary (not breathing hard at all), light physical activity (breathing hard a little), and moderate-to-vigorous physical activity (breathing hard a lot). Students also reported their perceived heat levels on a 3-point scale: "not at all hot," "a little hot," or "a lot hot" immediately after recess. Daily air temperature data at scheduled recess times were obtained from the nearest weather station.
170 students completed 981 surveys, with individual participation ranging from 2 to 11 surveys per student (mean = 5.8 surveys). Outdoor air temperatures during recess across the study period for schools in the sample ranged from 90°F (32.2°C) to 108°F (42.2°C); the mean temperature was 97.9°F (36.6°C). Across schools, students reported that an average of 34.5% of recesses were predominantly spent sedentary, 42.5% in light physical activity, and 23.1% in moderate-to-vigorous physical activity. These distributions remained relatively consistent over the six-week period. Students also reported feeling "a lot hot" in 45% of observations. Higher perceived heat was associated with greater physical activity intensity, and the authors also found that perceived heat did not meaningfully alter activity trajectories over the study period.
The authors note that the positive association between perceived heat and activity does not indicate causal directionality: because the surveys happened directly after recess, children's responses may likely reflect feeling especially hot after intense physical exertion, as opposed to higher heat encouraging intense play.
Regardless, their findings highlight a disconnect between children's activity and environmental heat risk during outdoor recess: children continued to engage in intense physical activity under extreme heat, even when they reported feeling hot, and did not change activity intensity across repeated heat exposures. The authors conclude: "Because children in school settings have limited capacity to independently regulate their thermal environment and may not have full access to critical protective resources (e.g., shade, water), these findings underscore the importance of proactive, adult-guided strategies to support heat-adaptive physical activity in schools rather than reliance on children's self-regulation."
The authors add: "One of the most interesting findings was that children continued to engage in physical activity, including moderate-to-vigorous activity, at a pretty consistent rate even when outdoor temperatures were extreme and they reported feeling very hot. These results highlight an important challenge for schools - rather than simply eliminating outdoor activity during hot weather, we need proactive strategies to help schools determine when and how children can safely remain active."
This project was supported by the 2023 Heat and Health CHS Pilot Grant Initiative at Arizona State University. Wilson was supported by the University of Arizona Cancer Center Office of Cancer Research Training & Education Coordination (CRTEC) during a portion of this work. Poulos and Vanos were also supported by funding from the National Science Foundation (NSF GEO/RISE-2521935). Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the NSF.
For related information, please visit ASU Heat Futures Lab, Active Schools & Communities Lab at Arizona State University , HUM.LAB , or HeatReadyTM Schools
In your coverage please use this URL to provide access to the freely available article in PLOS Global Public Health: https://plos.io/4sNnhav
Citation: Wilson K, Vanos J, Lim CC, Poulos A (2026) Children's physical activity during six weeks of school recess in hot weather: Associations with perceived and measured heat. PLOS Glob Public Health 6(11): e0007432. https://doi.org/10.1371/journal.pgph.0007432
Author Countries: United States
Funding: This work was supported by the 2023 Heat and Health CHS Pilot Grant Initiative at Arizona State University (AP and JV) which provided project support for recruitment incentives, materials, and supplies. No salary support was provided through this funding source. KW received salary support during a portion of this work from the University of Arizona Cancer Center Office of Cancer Research Training & Education Coordination (CRTEC). AP and JV received salary support during a portion of this work from the National Science Foundation (NSF 2521935). CL received salary support during a portion of this work from the National Institute of Environmental Health Sciences of the National Institutes of Health (R01ES034740, P20ES036112, P30ES006694, and P42ES00494). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
