Climate Costa Rica's year round climate is pleasant with naturally occurring breezes cooling down most of the coastal areas. Temperatures in the highlands and the mountains are warm by day and brisk at night giving an 'eternal spring' feeling. The average annual temperatures range from 31.7ºC (89ºF) on the coast to 16.7ºC (62ºF) inland. The rainy, or green, season lasts from May to December with noticeably drier days during the rest of the year. As far as climate goes, the late-December to mid-April dry season is the most pleasant. Although some roads are impassable in the wet season, it's still worthwhile to visit at time, and things are much quieter. April, May and mid-October to mid-December should give you the best of both worlds.