The climate in Guanacaste is clearly tropical, but with variations depending on the altitude. For example, in the lowlands of Guanacaste, the weather is usually arid and hot. The climate in Guanacaste in general is tropical dry. In the higher altitudes, the climate changes into a fresh and cold climate, especially the mountains tops of the different volcanoes, which rise above sea level to an altitude of around 6000 feet. The weather there is usually cloudy, cool and rainy.

Guanacaste is a region famous for its beaches. Sunny days are quiet abundant, around 200 days a year. The weather is usually dry, and therefore, during the dry seasons, it might come to the point where some areas have a lack of water. During the rainy season however, water is becomes almost too abundant, even creating some flooding in river beds areas near the Tempisque.