California has launched CalHeatScore, a new statewide tool led by the Office of Environmental Health Hazard Assessment (OEHHA) to rank extreme-heat health danger by ZIP code and link people to nearby cooling resources and safety guidance. The pilot system sorts risk into four categories (mild to severe) and is meant to drive clearer public messaging around heat, a hazard officials call a “silent killer.”
While OEHHA leads the program, the underlying heat-health model and statistical methods were developed by UCLA’s C-Solutions, led by Dr. David Eisenman. CalHeatScore builds on prior UCLA heat-mapping work by collaborating with Oregon State University’s John Molitor and Applied Climatologists’ Larry Kalkstein.
Unlike a typical heat warning system, 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 warnings based on 7-day advanced forecasts. Developers also emphasize that ZIP-code-level differences matter in regions like Southern California, where inland and coastal neighborhoods can experience very different heat risk on the same day. To view your ZIP code on the CalHeatScore warning system, visit: https://calheatscore.calepa.ca.gov/
Click to access the UCLA article and LAist article about the launch of CalHeatScore.
