The dry season runs from December to April and is the most popular time to visit. The sea is calm, the sky clear, and visibility underwater can exceed 30 metres. December and January bring the largest crowds of Colombian holidaymakers and the highest prices — book flights and accommodation well in advance. March and April are busy but slightly cheaper.
From June the trade winds build and short heavy showers become regular. The sea remains warm and diveable, but rough days are more common. Hurricane season officially runs from June to November; the archipelago is on the fringe of the main hurricane belt and direct hits are rare, but swells and rain can disrupt boat trips from September onwards.
The Green Moon Festival in September is the big annual event — a celebration of Raizal culture with drumming, dance, and a parade; worth timing a visit around if you can manage the wetter weather.