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Blog Post · May 20, 2024

Extreme Heat Takes a Toll on Californians’ Health

photo - child standing in front of a fan

As the summer season kicks off, Californians are feeling the heat—literally. According to PPIC’s Californians and the Environment surveys, concern about increasingly severe heat waves has been steadily rising since 2019. Last year, a record 85% of Californians expressed concern about heat waves, with the highest rates among African Americans (96%) and respondents making less than $40,000 a year (89%).

Despite a cooler-than-average summer last year, Californians face a growing risk of heat waves that will impact public health as climate change progresses. By 2050, health-impacting heat events will occur for two additional weeks each summer in the Central Valley and between four and 10 times more often in the Northern Sierra. What impact is this growing risk having on Californians’ health, and how can we prepare?

figure - Californians are increasingly concerned about heat waves

Improve data collection. Heat is considered one of the deadliest weather events, yet tracking the impact of extreme heat on public health remains a challenge. The data doesn’t always capture heat-related health impacts: hospital visits and deaths during heat waves can be attributed to other health factors. It’s also difficult to track long-term health complications due to prolonged and repeated exposure to extreme heat, like kidney and cardiovascular problems. But several studies provide an insight into this invisible toll. An analysis by the Los Angeles Times estimated that nearly 4,000 deaths between 2010 and 2019 could be related to extreme heat by calculating the number of excess deaths (deaths that exceed the expected numbers in the same period) during heat waves. UCLA researchers identified more than 8,000 excess emergency room visits a day during heat waves between 2009 and 2018.

Track and address disparities. Extreme heat risk is not the same for all Californians, and it can expose demographic disparities among California’s communities.

  • Black Californians have the highest heat-related mortality rate among all race categories, which is 1.5 times higher than the average: 0.28 per 100,000, compared to the average of 0.17.
  • Elderly people are 2.5 times more likely than the general population to die from extreme heat (0.44 per 100,000 for 65 and over, compared to the 0.17 average).
  • During the 2022 heat waves in Los Angeles County, people without secure housing were more than 50 times more likely to die a heat related death than the general population.
  • Outdoor and warehouse workers struggle during heat waves, especially in the absence of adequate precautions.
  • Those with health co-morbidities, such as diabetes, cardiovascular diseases, and kidney issues, tend to face higher risks during heat waves.
  • Low-income neighborhoods, which tend to lack shade, green space, and access to air conditioning, are more vulnerable to extreme heat than high-income ones.
  • Uninsured and low-income Californians may be unable to afford healthcare and as a result have to delay or skip seeking care, which exacerbates the health impacts.

Bolster infrastructure. The growing risk of extreme heat also exposes vulnerabilities in physical and social infrastructure. Extreme heat events can overwhelm healthcare resources, especially in areas that already struggle with limited capacity and service. When these events coincide with other climate events like wildfires, the resources might be stretched even thinner. Buildings in regions that have not experienced extreme heat events as frequently and severely in the past may lack adequate insulation or air conditioning. The urban heat island effect—in which densely concentrated pavement and buildings absorb and hold heat—and extreme heat events might be felt more severely in low-income communities that lack green spaces and tree cover. The time window for safe outdoor recreation, particularly in summer, might become more limited.

In response to this growing risk, California is continuing to invest in heat resilience:

  • Despite this year’s cuts to the state budget, under the governor’s May Revision proposal, the Extreme Heat and Community Resilience Budget Package from 2021 might maintain around $270 million in state funding for programs like green schoolyards, urban greening and forestry, and low-income weatherization programs.
  • Cal/OSHA recently approved the expansion of protections under the Heat Illness Prevention Standard to most indoor workers for the first time starting this summer, with the exception of state prisons. The standard used to only regulate outdoor work conditions.
  • The Extreme Heat Action Plan, released in 2022, sets goals to boost public awareness, build heat response capacity at the community level, improve infrastructure resilience against extreme heat, and deploy nature-based solutions to counter heat risks.

As the threat of extreme heat to Californians’ well-being grows, so does the need for new tools to manage the risk. State funding and new regulations will support heat resilience, but exactly how much funding is needed to address the growing heat risk remains unknown. Furthermore, additional funding may be necessary to maintain and enforce the new policies, particularly at the local level. Training health professionals and public health officials to better identify and track heat-related illnesses and fatalities can provide high-quality data to help target heat resilience policies. Lastly, expanding affordable healthcare to the most vulnerable, including low-income and uninsured Californians, during and in the aftermath of heat waves can help close the heat-risk gap among different demographic groups.


climate change Drought extreme weather health Health & Safety Net racial disparities Statewide Survey Water, Land & Air wildfires