The rainy season in Costa Rica runs from May to November, with the heaviest rainfall typically occurring in September and October. The rainy season is also known as the “green season,” as the rain helps to nourish the plants and keep everything looking lush and green. While the weather during the rainy season can be unpredictable, with rain showers often coming in short bursts, it is still a good time to visit Costa Rica, as the weather is generally warm and the rain can help to cool things off. The rainy season is also a good time to visit if you are interested in experiencing local festivals and cultural events, as many of these take place during this time of year.