California Governor Gavin Newsom has announced a new API for CalHeatScore, a critical tool designed to provide real-time, zip-code-level heat risk data to a wide array of stakeholders, enhancing public safety as warmer days approach. This initiative comes during National Heat Safety Awareness Week and ahead of Memorial Day, underscoring the state's proactive measures against extreme heat, which is the nation's leading cause of weather-related deaths.
CalHeatScore, initially launched last year, forecasts and classifies public health risks from heat and connects residents with protective resources. The new Application Programming Interface (API) makes this vital data accessible to application developers, weather services, local governments, non-profits, universities, medical providers, emergency responders, and data journalists. This integration allows for the development of community alerts, emergency response planning, and news reporting.
Governor Newsom said, "California is transforming data and technology into real protection, giving people the power to anticipate extreme heat and act in advance. As temperatures rise, this innovation helps safeguard lives, strengthen resilience, and ensure that no one is left behind." Kris Thayer, Director of OEHHA, added that tools like CalHeatScore and its API are "more crucial than ever" given early summer temperatures.
Extreme heat poses significant dangers, claiming more lives annually than fires and floods. California experienced its hottest summer in 130 years in 2024. Between 2013 and 2022, seven extreme heat events led to approximately 460 deaths, over 5,000 hospitalizations, and 344 adverse birth outcomes, alongside an estimated $7.7 billion in economic losses.
Developed by the California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA), CalHeatScore was mandated by Assembly Bill 2238 in 2022, making California the first state to implement such a heat classification system in 2025. The system integrates complex climate and health data with information on cooling centers and vulnerable populations, offering clear guidance and safety tips. The API is part of ongoing efforts to expand CalHeatScore's utility and keep Californians informed.