The climate of Puerto Rico falls into the tropical climatic zone. Temperatures are moderate year round, averaging near 80 °F (27 °C) in lower elevations and 70 °F (21 °C) in the mountains. Easterly trade winds pass across the island year round. Puerto Rico has a rainy season which stretches from April into November. The mountains of the Cordillera Central are the main cause of the variations in the temperature and rainfall that occur over very short distances. The mountains can also cause wide variation in local wind speed and direction due to their sheltering and channeling effects adding to the climatic variation. About a quarter of the annual rainfall for Puerto Rico, on average, occurs during tropical cyclones, which are more frequent during La Nina events.
Temperature – Temperatures range from 70 °F (21 °C) to 90 °F (32 °C) in the lower elevations, while higher elevations in the central part of the island experience temperatures between 60 °F (16 °C) and 80 °F (27 °C) year round. The temperature in the south is a few degrees higher than the north. Between winter and summer, there is only a temperature swing of around 6 °F (4 °C). This is mainly due to the warm waters of the subtropical Atlantic ocean, which significantly modify cooler air moving in from the north and northwest.
Rainfall – There is a pronounced rainy season from April to November. Due to the commonwealth’s topography, rainfall varies greatly across the island. Pico del Este averages 171.09 inches (4,346 mm) of rainfall yearly while Magueyes Island averages only 29.32 inches (745 mm) a year. There have not been any documented cases of snow falling within Puerto Rico, though occasionally it is brought in from elsewhere as a publicity stunt.
Sometimes, during showers and thunderstorms, waterspouts form off the coasts, frequently on the west coast. In the inner sea, tornadoes and hailstorms are possible. These thunderstorms can be a result from tropical waves, tropical cyclones, and frontal boundaries which become stationary across the region between fall and spring.