Urban Heat Islands in San Francisco

This map was created from data during a September 2022 heatwave as part of the Urban Heat Watch mapping project. After analyzing the data, they found that Mission Bay, Bayview-Hunters Point, and Outer Sunset were hotter than other neighborhoods as a result of their environmental design. 

Cooler areas on the map correspond to green spaces like Golden Gate Park. In these areas, vegetation and soil release moisture that evaporates and provides a cooling effect. 

Comparatively, hotter areas generally correspond to  urban areas densely packed with buildings, concrete, and asphalt that absorb heat during the day and release it later during the night. The Tenderloin and SoMa, both of which have the lowest percentage of tree cover in the city, experience some of the highest temperatures. 

Additionally, the topology of San Francisco also effects which areas experience the urban height island effect. The coolest area in the dead center of San Francisco benefits from a basin where cooler, dense air pools at night. Similarly, the Twin Peaks and Mount Davidson area midway in the city prevent cool coastal winds from reaching the eastern half of the city. 

San Francisco has some of the lowest air conditioning rates of any major city in the U.S., and as urban heat islands continue to spread and intensify, the city will have to address how these heat islands uniquely affect San Francisco's site and adapt in order to combat the rising temperatures.