Newsom unveils new tool to combat deadly California heat

Gov. Gavin Newsom unveiled CalHeatScore, making the state the first in the nation to launch a heat-ranking system designed to forecast and communicate extreme heat risks to residents. The announcement coincided with $32.4 million in funding for 47 California communities to develop heat mitigation infrastructure as record temperatures are expected this weekend.

The new tool addresses what state officials describe as the leading cause of weather-related deaths in California. Extreme heat claims more lives annually than fires, floods, or other climate-related threats, according to state data.

"Extreme heat kills — and with the federal government cutting the very programs that help forecast it, California is taking aggressive action to protect residents from the impacts of extreme heat and build resilience in our most vulnerable communities," Newsom said during the announcement.

CalHeatScore was developed by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment. The system combines ZIP code-level data to provide locally tailored guidance for residents, identifying vulnerable populations such as older adults and children while offering safety tips and heat illness recognition information.

The tool integrates multiple data sources, including locations of cooling centers and demographic information about heat-susceptible groups. State officials plan to use CalHeatScore across government agencies to mobilize resources more quickly and precisely to communities facing dangerous heat conditions.

"Every single preventable death is one too many," said Yana Garcia, California Secretary for Environmental Protection. "This groundbreaking tool will help Californians plan and respond so they can stay safe when a heat wave is about to strike."

The heat-ranking system operates similarly to hurricane categorization, providing residents with clear communication about the severity of approaching heat waves. This approach was recommended in 2021 by the California Department of Insurance's Climate Insurance Workgroup, which suggested California develop a system to better communicate the risks of deadly heat to communities.

Assembly Bill 2238, signed by Newsom in 2022 as part of a broader climate package, required the state to develop the statewide extreme heat ranking system. Assemblymember Luz Rivas authored the legislation codifying the insurance department's recommendation.

Nancy Ward, Director of the California Governor's Office of Emergency Services, described CalHeatScore as "an important tool to prepare Californians for extreme heat" that "helps increase our readiness for heat events and protect those at greatest risk."

The funding supports the Extreme Heat and Community Resilience Program, which aims to build infrastructure solutions and strengthen community resilience against extreme heat events. The grants target local, tribal, and regional efforts to combat dangerous heat exposure through long-term infrastructure investments.

Projects funded through the program combine physical infrastructure with nature-based solutions and in-home technology. Los Angeles County will work with local organizations to create safer spaces by planting tree canopies, installing water fountains, and hosting educational programming in parks. In Northern California, North Coast Opportunities and the Middletown Rancheria of Pomo Indians of California will partner to provide solar-powered air conditioning in vulnerable community members' homes.

Samuel Assefa, Director of the Governor's Office of Land Use and Climate Innovation, oversees the funding program. "With lives on the line each summer, the Extreme Heat and Community Resilience Program will provide critical infrastructure investments in heat vulnerable communities," Assefa said.

The funding builds on Newsom's Extreme Heat Action Plan, which was developed in collaboration with more than 20 state agencies and informed by input from over 1,000 individuals through listening sessions and public engagement. The grants respond directly to community needs while building on existing state programs.

California communities experienced their hottest summer on record last year in 130 years of data collection. A Department of Insurance report found that from 2013 to 2022, seven extreme heat events resulted in nearly 460 deaths, over 5,000 hospitalizations, and approximately 344 adverse birth outcomes.

State research indicates correlations between heat exposure and various negative health effects, including death, lower birth weight, and increased emergency room visits for conditions ranging from heart problems to mental health issues. Extreme heat also has significant economic impacts, resulting in an estimated $7.7 billion in lost wages, agricultural disruptions, and power outages.

The announcement comes as California faces water supply challenges related to increasing temperatures. The state expects to lose 10% of its water supply due to hotter and drier conditions, threatening water access for millions of residents.

During extreme heat periods, access to water becomes critical for preventing illness and death. As part of his May budget revision, Newsom proposed fast-tracking the Delta Conveyance Project, a water management and climate adaptation initiative aimed at improving the State Water Project that serves 27 million people and 750,000 acres of farmland.

State officials plan to continue gathering public input on CalHeatScore to shape future updates to the system.