DAILY CLIMATE REPORT - issued daily: Detailed daily weather statistics (usually for yesterday), including temperature, precipitation, degree days, wind, humidity, sunrise/sunset, and record temperature data for the following day.
In Costa Rica the average annual temperature is around 21 to 27 degrees Celsius or 70 to 81 degrees Fahrenheit and the coolest months of the year are November, December and January. The months March through May are the hottest months of the year, so make sure you protect yourself from the sun.
September Weather. The weather in Costa Rica during the month of September is one of extremes. Generally the Pacific side is at its rainiest, while the Caribbean side is experiencing the best weather of the year. The Northwest Pacific is the driest area on the Pacific side. Temperatures will be in the low to mid 80s during the day and a little cooler in the evening.