Looking at positive test rate, almost every state which saw upticks last week are in the southern half of the country. CA, NV, AZ, TX, OK, AR, MS, TN, AL, NC, SC, GA, FL. Presumably Louisiana didn’t because everyone there already got it. The other few states were rocky Mountain: utah, Wyoming, Idaho, MT which had higher than average temps in the preceding weeks including some days near or at 100.
So people go inside to air conditioning. I think it’s pretty clear that being inside a bigger risk than being outside. Closing beaches would then seem counterproductive. People should be encouraged to be outside as much as possible to stop the spread