Costa Rica - Climate and when to go to Costa Rica

Climate

The climate is idyllic. In the lowlands -which are dry in the Pacific Northwest and humid elsewhere- daytime temperatures range from the high twenties to mid-thirties C°. Usually low to mid-twenties C° at middle elevations, it can be as low as five to mid-tens C° at the top of the mountains. The Northwest has a fairly well-defined dry season from December to April. The dry season is a month or two shorter along the southern Pacific coast. July also tends to be a dry month on the Pacific slope.

When to go
 
The best time for Costa Rica travel depends on which attractions your clients want to focus on:
 
Beach
The best time to travel to Costa Rica is December through May on the Pacific side; don't go to the Caribbean in October or November, which is often flooded then.
 
Surfing and rafting
The best time to travel from March through November.
 
Costa Rican Attractions
Attractions such as fishing is a year 'round activity. However, the best fishing for marlin and sailfish is December through March in Quepos and Manuel Antonio, and in Guanacaste the rest of the year.
 
Volcanoes & Scuba diving and Snorkelling
If you want to explore the volcanoes, avoid rainy season (May-October). Too many clouds make it hard to see even an active volcano such as Arenal or Poas. This is true for scuba diving and snorkeling too, as the run-off reduces visibility.
 
Eco tours
The rainy season is fine as well when taking eco tours along nature trails and trips into the rainforest or cloud forest.