UCLA Fielding experts on southern California's extreme heat: "Knowing who is hit hardest is essential for planning targeted interventions"

Extreme heat is hitting southern California this week, in a rare early season heat wave that poses health risks to many communities. Record high temperatures have already been broken on the first day of the heat wave, which is expected to continue throughout the week.

Faculty and staff at the UCLA Fielding School of Public Health, including at the UCLA Center for Healthy Climate Solutions (C-Solutions), have expertise and tools, including the UCLA Heat Maps project, that can help address the risks.

"Heat maps reveal something temperature data alone can't: which communities are most vulnerable to heat-related health impacts," said Dr. David Eisenman, a physician and professor in the UCLA Fielding School's Department of Community Sciences and co-director of the Center.  "Knowing who is hit hardest is essential for planning targeted interventions - especially as heat waves grow more frequent and severe." 

Despite consistently high temperatures across southern California, communities experience and respond to heat differently. For example, outdoor workers, older people, and those without air conditioning are more vulnerable to heat illnesses. ZIP-code-level differences also matter in regions like Southern California, where inland and coastal neighborhoods can experience very different heat risk on the same day. Tools such as CalHeatScore and the UCLA Heat Maps reveal neighborhood-level impacts of extreme heat and equip residents, communities, and policymakers with tools to protect against heat-related health harms.

CalHeatScore, a statewide tool led by the Office of Environmental Health Hazard Assessment (OEHHA), ranks extreme-heat health danger by ZIP code and links people to nearby cooling resources and safety guidance. CalHeatScore is designed to reflect real health impacts, incorporating emergency-room visit patterns for heat-related illnesses (e.g. heat stroke, heat exhaustion, dehydration, etc.) alongside temperature forecasts to provide four categories of warnings based on 7-day advanced forecasts.

The UCLA Heat Maps, an innovative public health and climate equity tool led by C-Solutions, visualizes community-level heat-related health burdens. Using similar methods to CalHeatScore, the map shows excess emergency room visits attributable to extreme heat for each ZIP code in California from 2008-2018. These maps provide small area actionable data to prepare for worsening extreme heat events, and are currently being used to inform LA County’s Heat Action Plan.

Explore CalHeatScore and the UCLA Heat Maps.