The weather in Belize is subtropical and typically a bit more extreme than the weather in south Florida, meaning that it will be hotter in summer and colder in winter.
January: shoulder season – transition from the rainy season to the dry season
February through April: dry season – the best time to visit Belize
May: shoulder season – transition from the dry season to the rainy season
June through November: rainy season – hurricane season is July through October
December: shoulder season – transition from the rainy season to the dry season
https://backpackandsnorkel.com/Belize/#BestTime