On any given day, the historic French Quarter is its own sort of festival — but never more so than during the actual French Quarter Festival.

The 33rd edition of the self-proclaimed largest free festival in the South takes over much of the lower half of its namesake neighborhood Thursday through Sunday. Presented by Chevron, French Quarter Fest opens with a second-line parade from the 100 block of Bourbon Street to Jackson Square starting at 10 a.m. Thursday. When it concludes Sunday evening, more than 400 acts will have supplied more than 300 hours of live music for hundreds of thousands of locals and visitors.

Over the years, the French Quarter Festival has expanded its offerings — numerically and stylistically — to the point that its roster resembles that of the New Orleans Jazz and Heritage Festival, minus the major headliners. Once devoted mainly to traditional jazz — of which there is still plenty on the smaller stages along Bourbon and Royal streets — the fest now showcases every variety of indigenous south Louisiana music, from Cajun and zydeco to rap. By the weekend, 23 stages will stretch from the Old U.S. Mint on Esplanade Avenue to the far end of Woldenberg Riverfront Park.

With a picture-perfect weather forecast through the weekend, expect big crowds. Attendance will certainly be higher than in 2015, when rain, some of it heavy thunderstorms, bedeviled three of the four days.

The festival is produced by the nonprofit French Quarter Festivals Inc., led by Executive Director Marci Schramm. Sponsorships — including some sponsors solicited by individual bands — and the sales of food, beverages and merchandise keeps the festival free.

This year, that merchandise includes a limited-edition “Vic and Nat’ly” T-shirt by Bunny Matthews, the celebrated local cartoonist who has battled brain cancer since last summer.

Given the tenor of the times, expect enhanced security measures throughout the festival site, including bag checks at the entry points to the major stages along the Mississippi riverfront. Attendees are asked to leave firearms, pets, drugs and outside beverages at home.

Even well into its fourth decade, the festival is still finding new local bands to feature. But beyond the music itself, the French Quarter Fest offers an array of related attractions. Le Petit Theatre du Vieux Carre hosts a free film festival. Attendees can take free dance lessons at the French Market Traditional Jazz Stage and the Chevron Cajun-Zydeco Stage at the Bienville statue. Kids can frolic in a designated area at the Natchez Wharf.

On Saturday and Sunday, the “Let Them Talk” series inside the Old U.S. Mint presents prominent musicians discussing their craft. During a 2:30 p.m. session on Sunday, Irma Thomas and others will remember the late Allen Toussaint.

Toussaint also is the subject of an official French Quarter Festival after-party at the House of Blues on Friday at 9 p.m. Members of his band will back a parade of special guests, including pianist Davell Crawford, Meters guitarist Leo Nocentelli, guitarist Walter “Wolfman” Washington, trumpeter James Andrews, trombonist “Big” Sam Williams and singer Robin Barnes.

That event is ticketed. But the music on the streets of the French Quarter over the next four days is free — and there’s a lot of it.