Costa Rica’s tropical climate can be roughly divided into two seasons: Dry and Green. The dry season runs from December to April. The Green season begins in May and typically peaks in September and October. The climate in Costa Rica varies by region throughout the year, although the dry season tends to be less humid.
Altitude is the other major influence on climate with hot and dry days in the coastal areas and rainy and cool in the valley and mountains ranges. Casual, lightweight clothing and comfortable walking shoes are fine for most days. A waterproof jacket is recommended for cooler evenings and rainy weather. If you plan to do much ecotourism and wildlife viewing, browns and greens that blend in with your surroundings are best. For adventures, Quick-Dry comfortable clothing is recommended.