Early distancing can be very potent

Finally a rainfall paper that perhaps you can believe in!?:

We test whether earlier social distancing affects the progression of a local COVID-19 out-break. We exploit county-level rainfall on the last weekend before statewide lockdown. After controlling for state fixed-effects, temperature, and historical rainfall, current rainfall is a plausibly exogenous instrument for social distancing. Early distancing causes a reduction in cases and deaths that persists for weeks. The effect is driven by a reduction in the chance of a very large outbreak. The result suggests early distancing may have sizable returns, and that random events early in an outbreak can have persistent effects on its course.

Here is more from Rolly Kapoor, et.al.  Here is a relevant Twitter thread, via Gaurav Sood.