San Juan, Puerto Rico Climate & Monthly Averages

The climate of San Juan

San Juan has one of the steadier climates in our dataset. Average highs move only 3°C across the whole year - from 83°F (28°C) in January to 88°F (31°C) in July - so the practical difference between seasons here is rainfall and daylight, not warmth.

Climate quick facts

• Hottest month: July - highs near 88°F (31°C)
• Coldest month: January - highs near 83°F (28°C)
• Decade extremes (2015-2024): 97°F (36°C) high · 65°F (18°C) low
• Wettest month: September (22 rainy days) · Sunniest: June (12.2 h sun/day)
• Climate type: tropical wet-and-dry
• Annual swing: 3°C between the average warmest and coolest month · day to night: 6°C
• Months averaging 30°C or hotter: 6
• Average humidity: 77%

Temperatures through the year

Days and nights are about 6°C apart on average - narrower than about 89% of the cities we track. January is the coolest month, with highs of 83°F (28°C) and lows near 71°F (22°C). At its warmest, in July, San Juan runs to 88°F (31°C) in the afternoon and back to 77°F (25°C) by dawn. Across the gridded 2015-2024 daily record, the highest daily maximum for this location was 97°F (36°C) and the lowest daily minimum 65°F (18°C). Average highs hold at or above 30°C for 6 months of the year, May through October being the unbroken run.

Rain, sun and snow

June is the brightest month at 12.2 hours of sun a day, against an annual average of 11.1 - sunnier than 97% of the 3496 cities in our dataset. Between the average July and the average January lie 3°C, a narrower spread than all but 9% of the 3496 cities in our dataset. Precipitation concentrates in September - 6.1 inches (155 mm) on 22 days - and thins out by January.

How San Juan compares

• Rain or snow reaches the ground on 214 days a year - more wet days than 92% of the 3496 cities we track.
• San Juan averages 80°F (26°C) across the year - warmer than 91% of the 3496 cities we track.

Ranked against every city in our dataset, each measured on the same ten-year window.

Best time to visit San Juan

December to March is the sweet spot for San Juan - humidity and rainfall are at their lowest, which is what actually varies here. Expect 83°F (28°C) in the afternoon and around 15 days of rain in a typical month of it. For the same question asked the other way round, see where else is warm in December.

Pack for San Juan with light clothing for the warm months, proper waterproofs rather than an umbrella - wet days are the norm here and moisture-wicking fabrics for the humidity. Even in July, lows of 77°F (25°C) make an extra layer worth the space.