The tour will happen rain or shine. There is no cost for children ages 3 and under.
12 The National Mall via Washington Walks Tips
One suggestion: Bring bug spray!
The weather was sunny, windy, etc.. I wore a sweater, flip-flops, etc..
If you drive, make sure you get there well ahead of time. Parking is not easy around the mall at that time. Dress code : Comfortable shoes.
There's a bathroom stop about halfway through the tour.
Spray or bring insect repellent.
About a mile from the closest metro station.
Wear very comfortable shoes. You will get warmer during some of the walk.