In the Central Valley, where the main centres of population are located, the average temperature is 22°C (72°F) and the region enjoys a spring-like climate year round. In the coastal areas, the temperature is much hotter and humid, while the Pacific Northwest can be extremely hot and dry. The rainy season starts in May and finishes in November, although there are distinct regional variations. June and July are the wettest months, particularly on the Caribbean side, but the season can run from May until December.
The 'warm' dry season is December to May, though temperature differences between summer and winter are slight. March is the height of the dry season, and the humidity is lower at this time, making this a popular time for visitors. Volcano Arenal is notoriously hard to see due to the clouds, but the best time of year to give it a shot is during April and May.
Required clothing:Lightweight cottons and linens most of the year, warmer clothes for cooler evenings. Waterproofing is necessary during the rainy season. Loose-fitting clothing is best. Wear neutral browns and greens for birding and wildlife viewing. Always bring mosquito repellent for both day and night.
Costa Rica, lying between Nicaragua and Panama, is a complete coast-to-coast segment of the Central American isthmus. Its width ranges from 119km to 282km (74 to 176 miles). A low, thin line of hills that rises between Lake Nicaragua and the Pacific Ocean in Nicaragua, broadens as it enters northern Costa Rica, eventually forming the high, rugged, mountains in the Pacific Northwest and the centre of Costa Rica.
The southern half of the country is dominated by mountains of tectonic origin; the highest peak is Chirripó Grande, which reaches 3,820m (12,530ft). More than half the population live on the Meseta Central, a plateau with an equitable climate. It is the setting for the country's capital, San José. There are lowlands on both coastlines, mainly swampy on the Caribbean coast, with savannah and dry forest on the Pacific Northwest merging into mangrove and rainforest southward. Rivers cut through the mountains, flowing down to both the Caribbean and the Pacific.
