The high-season for Costa Rica tourism lasts from late November until April, when people from the northern latitudes are generally seeking warmer conditions. This also coincides with the "dry season" in Costa Rica, which could mean a little less rain during your time in the rainforest. As would be expected, tourism in the country is highest around Christmas and spring break. In general, tourism during the high-season will mean that good prices will be more difficult to find and attractions will be more crowded in spite of the fact that they will compare favorably to many other tropical tourist destinations throughout the world during this time period.
The "green season" is currently being used to refer to the tropical rainy season from May through Mid-Nov when tourism is not as intense. Tourism during this time of year can still provide for a wonderful experience, especially some of the more eco-touristy attractions. Rivers run higher, the rainforest becomes a little more mystical, and even the dry-forests of Guanacaste turn green and lush. Most places in Costa Rica receive their rain like clock-work near the same time on most days during this season so planning events is very possible. One pitfall is that many of the more unkempt roads become near impassible although by using professional transport services you can reduce the probability of getting stuck.
