Exploring the Influence of Summer Temperature on Human Mobility during
the COVID-19 Pandemic in the San Francisco Bay Area
Abstract
Heat related illnesses are one of the leading causes of weather-related
mortality in the United States, and heat extremes continue to increase
in frequency and duration. Public health interventions include
population mobility, including travel to central cooling centers or
wellness checks on vulnerable populations. Using anonymized cellphone
data from Safegraph’s neighborhood patterns dataset and gridded
temperature data from gridMET, we explored the mobility-temperature
relationship in the San Francisco Bay Area at fine spatial and temporal
scale. We leveraged spatial variability in median income and temporal
variability in COVID-19 related policies across two summers (2020-2021)
to analyze their influence on the mobility-temperature relationship. We
completed quantile regressions for a dataset stratified by income and
year. We found that mobility increased at a higher rate with higher
temperatures in 2020 than 2021. However, in 2021, the relationship
reversed for several wealthier income groups, where mobility decreased
with higher temperatures. We then augmented the analysis and calculated
a panel regression with fixed effects to characterize the
mobility-temperature relationship while controlling for temporal and
spatial variability. This analysis suggested that all areas exhibited
lower mobility with higher summer temperatures. However, similar to the
results of the quantile regression, the rate of decrease in mobility in
response to high temperature was significantly greater among the
wealthiest census block groups compared with the least wealthy. Given
the fundamental difference in the mobility response to temperature
across income groups, our results are relevant for heat mitigation
efforts in highly populated regions in current and future climate
conditions.