The weather in Costa Rica is a tropical / subtropical
largely influenced by its location near the equator and is
characterized by two main seasons : The dry season , from
December to April and the rainy season , from May until
November.
Although Costa Rica is a relatively small country , the
climate it greatly varied : The area of the beaches on
both sides of the country, the Caribbean and on the Pacific,
is with the highest heat stress in the country , while in
the central plateau and in the rainforest the weather is
more comfortable.
In San Jose , the capital and the central valley there
is " eternal spring " with average temperatures
about 22 degrees Celsius .
You can visit Costa Rica all around the year. Each season
has its benefits : in the dry season it is good to hike, the
visibility is better and there are more hours of
sunlight. At the rainy season there are fewer tourists, so
it is less crowded and the prices of accommodation and
services are lower , the rivers are full of rushing water
and the air is clear.
Links:
Go Visit Costa Rica Weather
Even if you have GPS it is good to have a good map.
Links for maps: