When to Go
Peak Season: January to April
The dry season has the most reliably sunny weather. But be aware that the climate swings wildly in the south, from bracing mountain air to steamy coastal humidity. In the mountains it's normally around 24°C (75°F) during the day and 10°C (50°F) at night. Temperatures can fall close to freezing on the upper slopes of Cerro de la Muerte and elsewhere, so be sure to pack warm layers. Temperatures in coastal areas are usually 24°C–32°C (76°F–90°F), but it's the humidity that does you in.
Off-Season: September to December
The rainy season can be very wet indeed, especially September through November. The wet season is longest in the Osa Peninsula, where showers usually last through January. Roads sometimes flood and many lodges close in the rainiest months (October and November). Elsewhere during the long rainy season, mornings tend to be brilliant and sunny, with refreshing rain starting in mid-afternoon. Many lodges offer discounted "green season" rates. Often, there is a two- or three-week period of dry weather with brilliant sunshine in late June into July, a mini-summer called el veranillo.
Shoulder Season: Early December and April to May
Early December, when the landscape is lush and green after months of rain and crowds of tourists have yet to arrive, can be delightful in most of the Southern Zone. April into May is another good time to visit, when crowds have thinned out and the rains are just starting to freshen up the landscape