July and August in on the French Riviera can be stifling, not only because of the intense heat but the crowds of tourists and vacationers. June and September are the best months to be in the region, as both are free of the midsummer crowds and the weather is summer-balmy. June offers the advantage of long daylight hours, although cheaper prices and many warm days, often lasting well into October, make September attractive. Try to avoid the second half of July and all of August, when almost all of France goes on vacation. Huge crowds jam the roads and beaches, and prices are jacked up in resorts. Don't travel on or around July 14 and August 1, 15, and 31, when every French family is either going on vacation or driving home.
Watch out for May, riddled with church holidays -- one a week -- and the museum closings they entail. Anytime between March and November will offer you a good chance to soak up the sun on the Côte d'Azur. After All Saints (November 1) the whole region begins to shutter down for winter, and won't open its main resort hotels until Easter. Still, off-season has its charms -- the pétanque games are truly just the town folks' game, the most touristy hill towns are virtually abandoned, and when it's nice out -- more often than not -- you can bask in direct sun in the cafés.