Most areas carry at least an 80 percent chance of rain Tuesday.
"We're going to roll rain or shine," Nancy Rogers, of the Gulf Coast Carnival Association, tells The Mississippi Press.
"Bring your raincoats and umbrellas and duck gear because we're gonna roll," she said. "This is not going to stop Mardi Gras."
The GCCA's parade will roll at 1 p.m. through downtown Biloxi.
Started more than 103 years ago, the parade is the largest on the Gulf Coast with more than 100 units.
Biloxi Police Chief John Miller suggests that parade-goers arrive early.
"The other thing we're asking is for people not to be in a hurry immediately after the parade," Miller said. "There's no reason to get on the road immediately after the parade passes you. We're not going to allow that for safety reasons."
At 3 p.m., the Krewe of Neptune parade will cap off the carnival season in Biloxi. It also rolls through downtown rain or shine.
In Bay St. Louis, the 6th annual Krewe of Diamonds parade will roll at 1 p.m. through downtown Bay St. Louis, Tequila Hall said.
Originally known at the Krewe of Real People, the krewe bills itself as the coast's only predominantly African-American krewe.