San Juan, the capital of Puerto Rico, sits on the northern Atlantic coast of the island in the Caribbean, on a low coastal plain and islets at approximately 18.47°N, 66.11°W. It has a tropical rainforest climate (Köppen Af) — hot and humid year-round, cooled by trade winds — with rain in every month and no true dry season, and it lies in the Atlantic hurricane belt.

There is no summer in the temperate sense: temperatures stay hot and steady, with daytime highs around 31–32°C and warm, humid nights near 24–25°C, tempered by the northeast trade winds. The wetter, stormier months run from August to November, coinciding with the peak of the Atlantic hurricane season, when powerful storms can strike the island directly.

There is no true winter, but the drier, more comfortable stretch from December to March brings slightly cooler temperatures around 28–29°C, lower humidity, more sunshine and steady trade winds, with nights near 21–22°C. This bright, breezy stretch is comfortably the best time of year and the peak tourist season.

San Juan receives on the order of 1,400–1,500 mm of rain a year, with rain in every month and no true dry season, though the heaviest falls come from August to November; the island's interior mountains and the El Yunque rainforest receive several times as much. Live rainfall, humidity, and pressure readings for the city are shown in the panels above.

Hurricanes define San Juan's weather risk: lying squarely in the Atlantic hurricane belt, Puerto Rico was devastated by Hurricane Maria in 2017, whose winds and catastrophic rainfall destroyed the island's power grid for months. Between storms, the steady trade winds keep the tropical heat comfortable year-round.

To follow any single measurement in San Juan more closely, use our live instruments: the online barometer for atmospheric pressure, the thermometer for temperature, the hygrometer for humidity, the anemometer for wind speed, the wind vane for wind direction, and the rain gauge for rainfall.