The climate in Puerto Rico is warm and tropical. With little variation in temperature throughout the year, the mercury never strays far from 85°F (29°C). Due to certain winds, the temperature in the south is usually a few degrees higher than the north, and the mountainous central interior is typically cooler than the rest of the island.
The hurricane season is between June and November, with the island being subject to severe tropical storms once in about every five years. The movement of major cyclones is tracked and can be predicted in advance, so there’s no need to worry. That said, it's best to be overprepared rather than underprepared for storms of this magnitude. Make sure you have access to non-perishable food, a few bottles of water and, if possible, a backup generator.
The dry season is typically from December to March, but you can expect short showers throughout the year. This is generally a pleasant period with plenty of sunny beach days.