Governments at all levels have much to do to respond to heat. We are helping governments launch, evaluate, and use data-driven frameworks, tools, networks, and programs to support local heat planning and action.
California Healthy Places Index: Extreme Heat Edition
Hot Observations About Shade in the United States (2025 research brief)
Based on data from our national Shade Map
This research brief summarizes the observations of our experts using our national Shade Map, created by the Luskin Center for Innovation and American Forests. The researchers find that 1) most cities lack sufficient shade, 2) trees provide 99% of shade when the sun is directly overhead, but buildings contribute more as the day progresses, and 3) many cities have a significant shade gap between neighborhoods.
Mapping Shade: A New Lens on Heat Equity (2025 data tool)
This new tool pinpoints where shade is lacking across 360-plus U.S. cities and towns.
This is the first time communities have an accessible way to see how much shade they have, where it is, and whether it comes from buildings or vegetation. The tool, developed in partnership with American Forests, aims to help federal, state, and local decision-makers identify existing “shade deserts” and prioritize investments to mitigate the impacts of extreme heat.
Space-Time Dynamics in Hazard Exposure Analysis: Smartphone Locations Show Pedestrian Routes Are Inflexible To Extreme Heat Events (2025 journal article in npj natural hazards)
Vulnerability to environmental hazards is spatially heterogeneous and dynamic. Static measures that are used to determine spatial heterogeneity in vulnerability are unable to capture temporal dynamics. To complement research on vulnerability to extreme heat, we investigated temporal and spatial trends in availability and use of shade by pedestrians during extreme heat events in a vulnerable neighborhood. Shade from trees and buildings calculated from LiDAR were paired with smartphone locations filtered to include outdoor pedestrians on an hourly basis for control and extreme heat days to study behavioral patterns for neighborhood residents, non-residents, and the unhoused population. High-use pedestrian locations showed little difference in activity between control and extreme heat days, especially during weekdays, but with greater variation on weekends. The results indicate inflexibility in space use, even during extreme heat. Outdoor heat mitigation strategies should consider bringing shade to the people in heavily used locations, as pedestrian behavior is inelastic.
Reducing Heat Risk for People Experiencing Unsheltered Homelessness (2023 article in the International Journal of Disaster Risk Reduction)
In this study, the researchers identified where unhoused residents in Santa Clara County were disproportionately exposed to heat and how they coped. They found that unhoused participants favored staying in places where they had more stability but these locations tended to have less access to shade and water, thus they faced difficult trade-offs.
Site Design and Human Heat Burden in Pacoima, California (2023 report)
A Case Study in Pacoima, California
This study examines how urban design influences the human experience of heat in Pacoima, a neighborhood in the San Fernando Valley region of Los Angeles. Researchers find the primary factor in reducing heat burden is the availability of shade.
Contributions of Roads To Surface Temperature: Evidence From Southern California (2023 story and article in Environmental Research Communications and Transfer Magazine)
Researchers find that the contributions of roads to land surface temperature are not large enough to offset conditions in the areas surrounding them. They also find that trees are the largest contributor to lowering land surface temperature, more so than impervious surface reflectivity.
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High Temperatures and Electricity Disconnections for Low-income Homes in California (2022 article in Nature Energy)
This study examines electricity use and disconnection data from 2012–2017. It finds that each additional day with a maximum temperature of 95 °F causes electricity expenses to increase by 1.6%, and the relative risk of disconnection to increase by 1.2%.
Urban Heat and Cool Design Facts (2022 factsheet)
This three-page fact sheet provides a visual introduction to the science of urban heat, the causes, and the cures. Metro regions, neighborhoods, and specific sites can be more or less hot because of the way they are built. Understanding what urban land features influence temperature across scales is essential for prescribing the correct intervention.
Housing and Urban Heat: Assessing Risk Disparities (2022 article in Housing Policy Debate)
The researchers find that households in detached single-family homes have the lowest heat risk and multifamily renters have the highest heat risk. AC availability is a major contributing factor and there are heat risk disparities for households in neighborhoods with larger proportions of Hispanic and Asian residents.
Households Living in Manufactured Housing Face Outsized Exposure To Heat and Wildfire Hazards: Evidence From California (2022 article in American Society of Civil Engineers)
This study analyzes the risk of extreme heat and wildfires on households living in manufactured housing, such as mobile homes, in California. The authors find that these households face consistently higher exposure to extreme heat and wildfires.
California Healthy Places Index: Extreme Heat Edition (2021 data mapping tool)
This index is an interactive tool designed to help the state ramp up its efforts to prepare for rising temperatures — visualizing where and who will be most affected, and where decision-makers should target investments.
Temperature, Workplace Safety, and Labor Market Inequality (2021 article in IZA Institute of Labor Economics)
This is one of the most comprehensive assessments of temperature on workplace health and safety, and the first assessment of potential implications for labor market inequality. The study finds that workplace injuries linked to heat are significant but extremely undercounted for both indoor and outdoor workers.
Coverage included features in The Guardian, The New York Times, and Los Angeles Times, along with testimony by Professor Park at a U.S. Congressional hearing.
Extreme Heat Vulnerability of Subsidized Housing Residents in California (2020 article in Housing Policy Debate)
This study examines whether Californians living in subsidized housing are more vulnerable to extreme heat than those living in unsubsidized housing. The researchers find that subsidized housing is disproportionately located in census tracts at the intersection of high projected extreme heat days (in 2040s), heat-sensitive populations, and barriers to adaptation. These findings indicate the need for targeted housing and land use policy interventions to reduce heat vulnerability.
Solar Reflective Pavements — A Policy Panacea To Heat Mitigation? (2020 article in Environmental Research Letters)
Awarded as the best 2020 paper by the Climate Specialty Group of the Association of American Geographers, this study collected the first field temperature measurements of solar reflective pavement. It found that surface temperatures decreased as expected, but human thermal comfort increased midday. It foregrounds the importance of planning context when locating cooling interventions.
Heat and Learning (2020 article in American Economic Association)
This research, and fact sheet, quantifies how cumulative heat exposure affects learning. Without air conditioning (AC), a 1°F hotter school year reduces student learning by 1%. The researchers also identify how school AC can mitigate this effect, and that low-income and minority students have less access to adequate AC, contributing to the racial achievement gap.
This research garnered over 100 media stories including an op-ed in USA Today, and coverage by PBS News, The Washington Post, TalkPoverty, KPCC Radio, ClimateWire, and America Adapts, among many other major outlets.
Hot Temperature and High Stakes Cognitive Assessments (2020 article in the Journal of Human Resources)
This study provides the first estimates of the impact of hot temperatures on high-stakes exam performance and subsequent educational attainments. Hot days reduce performance by up to 15% and have persistent effects on high school graduate status.
Media coverage: The New York Times, BBC News, The 74 Million, Joongang Ilbo (Korean Daily)
The Impact of High Temperatures on Delivery Timing and Gestational Lengths (2019 article in Nature Climate Change)
This study links early childbirths to hotter temperatures due to climate change. It received press coverage by CNN, TIME, The Conversation, and USA Today, among others.
Will We Adapt? Temperature, Labor and Adaptation to Climate Change (2018 working paper)
This national study explores heat-related labor impacts. Findings include that hot temperatures exert a causal negative impact on county-level payroll – reducing payroll by several percentage points in a 2◦C hotter year – with larger impacts in highly exposed industries, such as construction and manufacturing.
Maybe Next Month? Temperature Shocks and Dynamic Adjustments in Birth Rates (2018 article in Demography)
In this study, researchers estimated the effects of temperature shocks on birth rates in the U.S. between 1931 and 2010. They found that global warming is making it more difficult for couples to conceive. Specifically, days with a mean temperature above 80°F cause a large decline in birth rates eight to ten months later.
This study was widely cited by the media, including CNN, Reuters, CityLab, and more.