The dry season — late November through May — is the obvious window. Roads to Caracol and the Mountain Pine Ridge are dependable, the rivers run clear, and humidity drops to comfortable levels. December through April is peak; expect higher prices, busy ATM Cave bookings, and busier hotels in town.
The wet season (June to early November) brings afternoon rain rather than all-day downpours, and the jungle is at its greenest. ATM Cave can close after heavy rain when river levels rise, and the road to Caracol turns to mud, so plan with flexibility. September is the quietest month and the riskiest for hurricanes, which occasionally affect the area. Bird and orchid life peaks during the shoulder months of March-May and October-November.