Virginia Heat Watch: Collaboration to assess climate vulnerability at local to regional scales

Systematic studies of temperature using consistent, field-validated methods are needed to make inter- and intra-urban heat comparisons and to prioritize resources and mitigation strategies. This study investigated spatial patterns of heat hazard across 10 small- to medium- sized cities in Virginia, USA, using a community science approach. Air temperature data were collected on a high-heat day in July 2021, employing a network of 213 volunteers. Geolocated one-second temperature and humidity measurements were used to create and validate 10-m resolution temperature models for each locality. Results indicate substantial intra-urban temperature differentials even in the smallest localities, averaging 3.2 °C for the morning, 5.1 °C for the afternoon, and 4.9 °C for the evening. The average cooling rate for the region was 0.28 °C per 10 % increase in tree cover. Census Block Groups with highest percentages of people of color and historically redlined neighborhoods exhibited elevated temperatures, highlighting environmental justice (EJ) implications. Socioeconomic variables less commonly used in EJ studies, such as educational attainment and employment status, were predictive of high-temperature areas in the smaller localities. Findings underscore the broad range of urban heat drivers and illustrate how community-based data can be used to prioritize policy and actions addressing extreme heat at local and regional scales. • Community-science approach to map temperature for 10 localities in Virginia, USA. • Afternoon temperature varied within a locality by 5.1 °C on average (range 2.8–8.3). • Even the two smallest localities had afternoon variability of at least 5.3 °C. • Neighborhoods with more people of color and HOLC redlining history were hotter. • Tree cover was highly correlated with temperature variability at multiple scales.