Geography and Demographics of Extreme Urban Heat Events in Santa Clara County, California

Summer heat waves inNorthern California continue to break records for extreme temperatures and put vulnerable urban populations at increasing risk for adverse health impacts. An analysis of Landsat land surface temperature data was conductedin this study to better understandthe geography and demographics of extreme urban heat events in Santa Clara County and the city of San Jose, California. The influence of several urban cover features including streets/roadways, parcel sizes and densities, impervious surfaces, and irrigated shrub/lawn cover were determined for county-wide surface heat patterns in early August 2020. Results showed that the surface temperature of the largest impervious (high-asphalt) surface features was significantly higher, at a mean value of 45°C, than the majority of the other areas across the entire county. In contrast, urban tracts with even partial coverage by irrigated green lawns, shrubs, and small trees had notable cooling effects on summer surface temperatures. Social demographic and household population variables from the U. S. Census Bureau were correlated against satellite surface temperature by census tract to reveal significant associations of family structure and education levels with local neighbourhood heat conditions.