Belize Barrier Reef in September

November through April offers the best conditions with calm seas and minimal rain. Water temperature stays around 80°F year-round, so you won't need a thick wetsuit. December and January see the clearest water visibility, often exceeding 100 feet at sites like the Blue Hole. But here's the trade-off: this is also peak season, so expect higher prices and more crowds at popular spots. May through October brings afternoon thunderstorms and rougher seas, but dive operators still run trips most days. Hurricane season technically runs June through November, though direct hits are rare. Whale shark season peaks from March through June at Gladden Spit, making spring visits extra special. The shoulder months of November and April offer the sweet spot of good weather and fewer tourists.