The survey, the 30th wave of a nationally representative panel study, was conducted Aug. 4-17, 2026, among 1,904 empaneled U.S. adults by SSRS, an independent research company, using both web and telephone interviews. The margin of sampling error for the full sample is plus or minus 3.2 percentage points at the 95 percent confidence level, and the data were weighted to reflect the U.S. adult population. Sixty-five percent of respondents said climate change is increasing the risk of heat-related illnesses, respiratory diseases, and insect-borne diseases. That figure is unchanged from August 2025, when it also stood at 65 percent, and from July 2024, when it reached 67 percent, but it is significantly higher than the 58 percent recorded in November 2023. The trajectory suggests a durable shift in public perception rather than a temporary spike tied to any single weather event.

Americans also broadly recognize that heat waves themselves are intensifying. Sixty-two percent say U.S. heat waves are becoming more frequent and more intense than in the past, statistically unchanged from 61 percent in August 2025, 65 percent in July 2024, and 58 percent in November 2023. The survey measured four categories of extreme weather and their effects on daily routines. Extreme outdoor heat topped the list, with 76 percent of respondents reporting that it affected their daily activities at least sometimes over the past year. Poor air quality resulting from wildfire smoke came next at 38 percent, while flooding (20 percent) and tornadoes or hurricanes (11 percent) were cited far less often, consistent with their lower frequency. Notably, the more frequently respondents reported that extreme heat, poor air quality, or flooding had disrupted their daily activities, the more likely they were to believe that climate change is raising the risk of heat-related, respiratory, and insect-borne illnesses.

The financial toll of extreme weather is also registering in household budgets. Nearly half of Americans, 46 percent, say that during the past year they faced unexpected utility expenses caused by storms, flooding, heat, or wildfires, statistically unchanged from 45 percent in August 2025. Thirteen percent reported unexpected homeowner’s insurance premium expenses from these causes, a significant decline from 18 percent a year earlier, while 8 percent reported unexpected health care expenses, unchanged from August 2025. Ken Winneg, APPC’s managing director of survey research, said the pattern reflects a broader transformation in how extreme heat fits into everyday life. “Extreme heat is no longer just an occasional inconvenience,” Winneg said. “It is affecting Americans’ household budgets and daily routines, from electricity bills to simply going outside.”

When asked specifically about the impact of extreme heat on their activities and lifestyle over the past year, majorities reported at least a minor effect across several domains. Eighty-two percent said extreme heat had a major or minor impact on their electricity bills, 75 percent on outdoor activities, 56 percent on exercise routines, and 56 percent on sleep. Several of these measures have climbed since August 2025: the share reporting a major or minor impact on exercise and sleep rose to 56 percent from 50 percent, and the proportion reporting effects on pets increased to 45 percent from 37 percent, all statistically significant increases. The data paint a picture of heat as a persistent, ambient stressor that shapes decisions about when to exercise, how well people sleep, and even how families care for their animals, rather than a rare emergency confined to the hottest afternoons of the season.

Despite this widespread exposure, public awareness of protective resources remains strikingly low. Sixty-five percent of Americans say they do not know the location of a cooling center they could go to in the event of extreme heat, while just 35 percent say they know where one is located. That knowledge level has shown little recent movement: 35 percent knew a cooling center location in August 2025 and 33 percent in July 2024, although the current figure is significantly higher than the 30 percent recorded in November 2023. Laura A. Gibson, an APPC research analyst, argued that the gap represents a communication failure that communities can address. “As we continue to experience extreme heat,” Gibson said, “communities need to do more to make the public, particularly vulnerable populations, aware of these cooling facilities.”

Unhealthy air quality, which is closely related to extreme heat through wildfire activity, has also become a more visible problem. During the summer of 2026, much of the nation experienced smoky and hazy conditions from wildfires. Six in 10 Americans, 60 percent, say the area where they live experienced days in the past three months when local health authorities reported that the air quality was unhealthy, up significantly from 48 percent in August 2025. Another 24 percent said their area did not experience such days, and 16 percent were unsure. The American Lung Association’s “State of the Air” 2026 report found that 44 percent of Americans live in areas earning failing grades for unhealthy levels of ozone or particle pollution, providing an independent corroboration of the public’s reported experience.

People who reported unhealthy air in their area took a variety of protective measures, several of which have become more common over time. Eighty-two percent said they responded to local authorities’ air-quality warnings by staying indoors more than they typically would, up from 76 percent in August 2025 and 74 percent in August 2023. Fifty-one percent closed their windows, compared with 45 percent in August 2025 and 48 percent in August 2023. Forty-eight percent turned on the air conditioning, statistically unchanged from 47 percent in August 2025 but significantly higher than 37 percent in August 2023. Twenty-two percent used a room-air purifier, compared with 19 percent in August 2025 and 17 percent in August 2023, and 12 percent wore a KN95 or N95 mask outdoors, up significantly from 7 percent in August 2025 and statistically similar to 9 percent in August 2023.

Looking ahead, a majority of Americans expect the dangers of extreme heat to intensify. Nearly six in 10, 59 percent, say people in their community will be more likely to experience heat stroke caused by extreme heat waves in the next 10 years. Twenty-nine percent said people will be about as likely to experience it, 4 percent said less likely, and 8 percent were unsure. That expectation is essentially unchanged from August 2025, when 59 percent anticipated greater risk, and July 2024, when 58 percent did, but it remains significantly higher than the 52 percent recorded in November 2023. The consistency of this outlook across three annual survey waves indicates that anticipation of worsening heat risk has become a settled feature of public opinion rather than a reaction to any single summer.

Knowledge of the specific symptoms of heat-related illness, however, remains uneven, and the survey identified notable gaps in health literacy. In August 2026, 88 percent of Americans correctly identified dizziness as a sign of heat-related illness, 83 percent identified nausea, and 72 percent identified hot, red, dry, or damp skin. But only 47 percent identified cold, pale, and clammy skin as a symptom, even though that presentation is a recognized warning sign. Just 5 percent incorrectly identified hunger as a symptom. “Most Americans recognize that climate change is increasing the risk of heat-related and other illnesses, but our findings show that recognizing the risk doesn’t always translate into knowing the signs of heat-related illness,” Winneg said. “That knowledge can be especially important as extreme heat becomes an increasingly common part of Americans’ lives.”

Two further knowledge gaps stand out in the data. Only 32 percent of Americans know that pregnant people exposed to extreme heat are more likely to deliver their babies early than pregnant people who are not exposed. Nearly half, 49 percent, said they were not sure, 17 percent incorrectly said exposed pregnant people are just as likely to deliver early, and 3 percent said they are less likely to do so. That level of knowledge has not changed significantly from August 2025, when 33 percent knew the fact, or July 2024, when 30 percent did, although it is significantly higher than the 24 percent recorded in November 2023. Meanwhile, most Americans do correctly identify who is most vulnerable to fatal heat: 69 percent said heat-related deaths are most common among adults ages 65 and older, while 8 percent said children, 2 percent said adults ages 21 to 40, and 4 percent said adults ages 41 to 64, with 16 percent unsure. That figure is unchanged from August 2025 but significantly higher than the 62 percent recorded in August 2022.

Taken together, the survey results suggest a public that has absorbed the reality of a hotter, smokier, more disruptive climate into its everyday routines and expectations, even as critical gaps persist in knowledge about protective resources and medical warning signs. The APPC’s Annenberg Science and Public Health survey panel has been tracking American public knowledge, beliefs, and behaviors regarding vaccination, Covid-19, flu, RSV, climate, and other consequential health issues, providing one of the longest-running longitudinal windows into how health perceptions evolve alongside environmental change. In addition to Gibson and Winneg, the ASAPH survey team includes Patrick E. Jamieson, director of the Annenberg Health and Risk Communication Institute, which oversees the survey; research analyst Shawn Patterson Jr.; and Kathleen Hall Jamieson, APPC’s director emerita. As records continue to fall and heat becomes a structural feature of American life, the survey’s authors suggest, closing the gap between risk awareness and practical preparedness will be one of the most consequential public health communication challenges of the coming decade.

Subject of Research: Public perceptions of climate change's health effects during the hottest U.S. summer on record

Article Title: In hottest summer on record, 2 in 3 Americans say climate change is increasing heat-related illnesses

Article References: In hottest summer on record, 2 in 3 Americans say climate change is increasing heat-related illnesses. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: extreme heat, climate change, heat-related illness, Annenberg Public Policy Center, ASAPH survey, air quality, wildfire smoke, cooling centers, heat stroke, public health, NOAA, household costs

The study, led by environmental epidemiologist Amruta Nori-Sarma of Harvard T.H. Chan School of Public Health in collaboration with colleagues at Truveta, Harvard, and Boston University, exploited a technological capability that earlier generations of heat researchers lacked: continuously refreshed electronic health record data. Rather than waiting months for claims data to be processed and aggregated, the team drew on state-day counts of emergency department visits from 19 eastern states, allowing them to quantify the health burden of the summer 2025 heatwaves while the season was still underway. In total, the analysis encompassed 8,169,637 emergency department visits recorded during the warm seasons of 2023 through 2025, providing a robust historical baseline against which the 2025 episodes could be compared.

The two heatwaves under scrutiny were stark in their timing and severity. The first gripped the region from 22 to 25 June 2025, and the second returned from 10 to 13 August 2025, engulfing the eastern United States in conditions that triggered National Weather Service heat alerts across much of the study area. To estimate how many visits these episodes caused, the researchers compared observed visit counts during the heatwave windows with counterfactual predictions of what visits would have been under typical temperature conditions, using temperature-health associations estimated from the prior three warm seasons.

Technically, the analysis rested on a conditional Poisson model, a statistical framework well suited to time-series data on disease counts. The researchers stratified time by year, calendar month, and day of week, with stratum-specific fixed effects that absorb routine patterns in healthcare utilization, such as weekday and seasonal variation. This design effectively compares hot days with cooler days occurring under otherwise similar conditions, a strategy closely related to the time-stratified case-crossover approach widely used in environmental epidemiology. Temperature exposure was modeled using distributed lag non-linear models, or DLNMs, which capture two crucial features of heat’s health effects simultaneously: the non-linear dose-response relationship between temperature and risk, and the fact that effects unfold over multiple days, with heat stress on one day influencing emergency visits over a window of zero to four days afterward.

The headline numbers were striking. During the June 2025 heatwave, the researchers estimated that 9.2 percent of all-cause emergency department visits were attributable to heat over the zero-to-four-day lag window, with a 95 percent confidence interval of 6.2 to 11.6 percent. During the August heatwave, the attributable fraction was 8.3 percent, with a confidence interval of 6.0 to 10.1 percent. In plain terms, roughly one in every eleven or twelve people who walked into an emergency department in these nineteen states during those weeks was there, at least in part, because of extreme heat. Similar patterns emerged when the team examined cumulative lags and cause-specific outcomes, indicating that the association was not an artifact of a single modeling choice.

Because the underlying data included diagnostic information, the researchers could decompose the burden by cause. Beyond direct heat-related illness diagnoses, they tracked emergency visits for kidney disease and for mental health conditions, both of which have well-documented physiological links to heat exposure. Kidney disease is acutely sensitive to dehydration and thermal strain, while a growing body of literature connects high ambient temperatures to psychiatric crises, including exacerbations of mood disorders and substance-related emergencies. The lag-specific analyses showed that the association between the 99th percentile of daily maximum temperature, about 36.9 degrees Celsius, and the sample median of 27 degrees Celsius was strongest on the same day for direct heat illness, while kidney and mental health outcomes followed somewhat different lag structures, consistent with the diverse physiological pathways through which heat injures the human body.

Those pathways are worth spelling out. Extreme heat forces the cardiovascular system to work harder, shunting blood toward the skin to dissipate warmth and increasing cardiac output, changes that laboratory studies involving more than 400 controlled heat exposure experiments have documented in detail. In people with preexisting heart disease, this added strain can precipitate decompensation. Dehydration concentrates the blood and promotes the formation of kidney stones and acute kidney injury, particularly in older adults and in people taking common medications that impair thermoregulation or fluid balance. Meanwhile, heat disrupts sleep, alters neurotransmitter function, and can increase impulsivity and aggression, mechanisms that plausibly underlie the observed rise in mental health emergency visits during hot weather.

The heterogeneity analyses added an important dimension to the findings. By fitting subgroup models for six age groups, three US census regions, and both sexes, the researchers probed whether the temperature-emergency visit association varied across populations. The results, visualized in forest plots comparing rate ratios at lag zero, showed differences by age, region, and sex, echoing decades of evidence that the very young, older adults, and residents of areas unaccustomed to extreme heat bear disproportionate risk. The state-specific exposure-response functions also revealed geographic variation: states with historically milder summers tended to show steeper increases in emergency visits per degree of warming, a pattern consistent with the idea that populations adapt, physiologically and infrastructurally, to the temperatures they usually experience, and that anomalous heat is most damaging where it is least familiar.

Methodological sensitivity checks strengthened the study’s credibility. The team replicated the primary analysis using daily average temperature instead of daily maximum temperature, and separately extended the lag window from four to seven days; both variations reproduced the central findings. Exposure data were drawn from the Open-Meteo weather API and National Weather Service records, and heat alert dates by state were compiled from National Weather Service advisories, allowing the investigators to anchor their heatwave definitions in the same official warnings that reached the public during those weeks. All analytic code, including the data extraction scripts, DLNM fitting routines, meta-analysis, and attributable burden estimation, has been made publicly available on GitHub, an unusual and welcome degree of transparency for a rapidly produced surveillance analysis.

The broader significance of the study lies less in any single percentage than in what it demonstrates about the future of climate-health surveillance. Traditional epidemiology delivers its verdicts long after the disaster has passed, when the findings can inform the next heat season but not the current one. By contrast, a near-real-time pipeline built on continuously refreshed electronic health records can tell public health officials, while a heatwave is still unfolding, how many excess patients are arriving, which conditions are driving the surge, and where resources are most strained. The authors argue that this capability should become a standing component of heat preparedness, complementing heat action plans and warning systems whose effectiveness, demonstrated in cities from Philadelphia to Montreal, depends on knowing when and where the danger peaks. As climate change renders summers like 2025 more frequent and more intense, the study suggests that the emergency department itself, properly instrumented, can serve as an early-warning sensor for the health impacts of a warming world, and that the true toll of extreme heat is far larger than the narrow category of heatstroke diagnoses would suggest. Nearly a tenth of all emergency care during those scorching weeks was heat’s shadow, and counting it in real time may be the first step toward preventing it.

Subject of Research: Attribution of summer 2025 US heatwave emergency department visits using electronic health records

Article Title: Impact of the summer 2025 heatwaves on emergency department visits in the USA

Article References: Nori-Sarma, A., Cartwright, B. M., Zanobetti, A., Pastwa, A., Stucky, N., & Willis, M. D. (2026). Impact of the summer 2025 heatwaves on emergency department visits in the USA. Nature Health. https://doi.org/10.1038/s44360-026-00194-y

Image Credits: AI Generated

DOI: 10.1038/s44360-026-00194-y

Keywords: heatwaves, emergency department visits, electronic health records, extreme heat, public health surveillance, climate change, epidemiology, distributed lag non-linear models, heat-related illness, kidney disease, mental health, United States