Planning for the weather is an important factor for making your trip to Costa Rica a success, especially when you're splurging. The hottest months are usually February and March, with an average temperature of 23°C, while the coldest months are August and September, with an average of 17°C. Between January and March, the daytime average is 25°C and the night-time average is 21°C. Between April and June, temperatures average 24°C during the day and 17°C at night. Between July and September, the temperature averages 20°C during the day and 15°C at night. Between October and December, the average temperature is 23°C during the day and 16°C at night.