High Season: Also known as the Dry Season is from mid-November to late April. It is considered summer for the Costa Ricans. The days are filled with blue skies from sunrise to to sunset and daytime temperatures will hover around 32 degrees Celsius (90 Fahrenheit). This is the most popular time of year for many travellers, especially those looking to get away from the cold snowy winters. Prices for accommodations, transportation and tours are highest during this season. Mid-November to mid-December can be pre-high season. As the climate transitions from the rainy season to the dry season there may still be a few, typically short-lived, afternoon showers. You can often find better prices during this time while still enjoying mostly excellent weather.
Green Season: This lush season is considered part of the wet or rainy season by some. It spans form May through till the end of August. During this season the sun shine typically shines in the morning but it will often rain towards the late afternoon. The countryside is very lush and colourful during this season. It is also a wonderful time for many activities such as whitewater rafting, surfing, turtle and whale watching.
Low Season: Truly the Wet Season in Costa Rica are the months of September and October. Although there is still a lot to see and do during this season, the activities may need to be planned around the heavy rains.