God is in the rain: the impact of rainfall-induced early social distancing on COVID-19 outbreaks

We measure the benefit to society created by preventing COVID-19 deaths through a marginal increase in early social distancing. We exploit county-level rainfall on the last weekend before statewide lockdown in the early phase of the pandemic. After controlling for historical rainfall, temperature, and state fixed-effects, current rainfall is a plausibly exogenous instrument for social distancing. A one percent decrease in the population leaving home on the weekend before lockdown creates an average of 132 dollars of benefit per county resident within 2 weeks. The impacts of earlier distancing compound over time and mainly arise from lowering the risk of a major outbreak, yielding large but unevenly distributed social benefit.