The temporary stop signs will be set up for six to eight weeks, officials said.
The speed limit change will begin on August 1. "Drive 25" signs and magnets will be available July 30.
See which roads will be closed for Saturday's 5K event.
The heavy rains have caused flooding throughout the city.
Starting May 20, Harrison Avenue will be closed between Main and President.
The 5K will close some roads in downtown Wheaton between 8:45 a.m. and 11:15 a.m. Saturday.