The Bahamas has two clear seasons. The dry season runs from December through April — cooler temperatures (around 21–27°C / 70–80°F), low humidity, and minimal rain. This is peak tourist season: prices are higher, hotels fill up, and Nassau's cruise-ship crowds are at their thickest. Book well in advance if you're coming between Christmas and Easter.
The wet season runs from May through November. Temperatures climb to 29–32°C (84–90°F) with higher humidity, and afternoon rain showers are common. Hurricane season officially runs June through November, with September the most active month. That said, direct hits on the Bahamas are relatively rare, and storms are well-tracked — with some flexibility in your plans you can usually dodge bad weather.
The shoulder months of May and November offer a reasonable compromise: fewer crowds, lower prices, and weather that's warm without being oppressive. The Exumas and outer islands are at their most beautiful in calm summer conditions, when the water is flat and visibility for snorkeling and diving is excellent.
Junkanoo draws the biggest crowds over Christmas and New Year. If you want to see it, plan around Boxing Day (26 December) or New Year's Day in Nassau, when the main parades run through the night on Bay Street.
For diving and fishing, the Bahamas is good year-round. Bonefishing is best from November through June when the fish are most active in the shallows. Blue marlin peaks between May and August.