San Francisco selected for national heat mapping project to help address health inequities related to extreme heat

The project is now recruiting volunteers to collect data to understand how heat is distributed across the City and identify urban heat islands.
June 16, 2022

SAN FRANCISCO, CA---San Francisco has been selected as one of 14 U.S. cities to participate in a national project called Urban Heat Watch to better understand the relationship between climate change, extreme temperatures, public health, and the built environment. The project is now asking for approximately 50 volunteers to join the effort to identify urban heat islands by attaching heat sensors to their vehicles.  

Urban Heat Watch, sponsored by the National Oceanic and Atmospheric Association (NOAA), will allow the City to measure how temperatures differ from neighborhood to neighborhood. The project marks an important first step to addressing health inequities related to extreme heat events. After attaching the heat sensors, volunteers will be asked to drive their vehicles along pre-determined routes across San Francisco to collect temperature and humidity data that will inform urban heat island maps, like the ones shown here. City officials, public health experts, climate specialists, and community activists will use these maps to understand and measure heat-related impacts at a neighborhood-by-neighborhood level and advocate for appropriate resources to reduce those impacts 

“We know that the conditions of extreme heat and poor air quality caused by climate change can have detrimental health impacts and exacerbate health inequities among communities of color and among medically vulnerable individuals,” said Director of Health, Dr. Grant Colfax. “There are many social and health factors that cause these inequities and so this project is important in ground-truthing where communities are at higher health risk, so we can use this data to consider ways to best support them.” 

San Francisco is particularly vulnerable to the public health impacts of extreme heat. That is because our infrastructure, like housing and office space, is developed for cool coastal temperatures, and our bodies are not acclimated to extreme heat. As a result, San Francisco experiences higher increases in emergency department visits during extreme heat events compared to elsewhere in the state. These vulnerabilities become even more pressing as extreme heat events and wildfire smoke increase in frequency and intensity. The impact is especially acute for populations with higher sensitivities to extreme heat, such as older adults, children, people with diabetes or asthma, unhoused persons, and those without the means to relocate or find temporary relief. 

“Extreme heat is increasingly impacting residents of San Francisco and it’s imperative that we develop plans, programs, and infrastructure to protect vulnerable populations. Knowing where the heat impacts are most severe is a critical first step to ensuring those efforts put a community’s health and resilience at the top,” said Brian Strong, San Francisco’s Chief Resilience Office and Director of the Office of Resilience and Capital Planning. 

San Francisco joins Austin, Portland, Atlanta and over 35 other cities to participate in NOAA’s Urban Heat Watch campaign since 2017. Cities from past campaigns have used their heat island maps to develop immediate action plans, such as adding cooling stations to bus shelters, educating residents and policymakers, and informing new public health experts and researchers.  

The San Francisco Urban Heat Watch campaign brings together City agencies--the Office of Resilience and Capital Planning, Department of Public Health, Department of the Environment, and Department of Emergency Management--with two community-based nonprofits focused on improving health and sustainability outcomes in their communities--Brightline Defense Project and NICOS Chinese Health Coalition, who will support on the ground work. 

“We joined this effort because natural disasters such as extreme heat disproportionately impact people of color and marginalized communities such as those residing in Chinatown,” said Kent Woo, Executive Director of NICOS. "We are proud to partner with the City and the Urban Heat Watch project to empower our ability to monitor and address the effects of extreme heat."  

Community members who are interested in supporting the Urban Heat Watch project by volunteering to collect heat data are encouraged to sign up at For questions about the project, please contact Alex Morrison ( or Matt Wolff ( 

The maps created from the Urban Heat Watch project will support a new cross-sectoral and interdepartmental City initiative to improve San Francisco’s resilience to heatwaves and wildfire smoke. The Heat and Air Quality Resilience Program (HAQR) will prepare San Francisco for the health impacts of extreme heat and wildfire smoke events. HAQR will design and implement strategies to increase the City’s resilience to extreme heat and wildfire smoke events year to year. The HAQR initiative is co-led by the San Francisco Department of Public Health, the City Administrator’s Office of Resilience and Capital Planning, and the San Francisco Department of Emergency Management.