Hopefully, they will go shopping when its raining.
I'd rather go to Mogadishu or Beirut in the 1980s than the Outlet Malls in Rehoboth on a beach season day when it was raining.
One (weekday/non-holiday) afternoon a couple summers ago I decided I finally had to do my annual clothes shopping.
It happened to rain that day but I thought nothing of it. Then I got there and it was a war zone. Just unbelievable sea of humanity, clothes strewn everywhere on the floor like looters had been through. It took me 45 minutes to get out of the parking lot of one of the outlets because of the traffic.
Given the forecast for the entire weekend is temps in the 50s and rain, I can't even begin to imagine what the outlets will be like. I bet you could literally spend an hour or two simply trying to get into or out of one of them in a car.
Of course, I've never understood the whole going to the beach thing on Memorial Day or Labor Day weekend, either

Memorial Day, especially. The water on the beaches right now is 52 degrees. But even in a normal weather year, on Memorial Day the water temps are pretty much always far too cold to go in the water. Fishing makes much more sense at least but man, I don't think I could stand any of the public shore fishing areas on one of the Holiday weekends.