Verdict: Fair month
San Juan Weather in August
August runs warm in San Juan, with daily highs around 31°C (88°F) and nights near 25°C (77°F). It's also the wet side of the calendar: rain falls on about 19 days, so build flexibility into plans. August is workable in San Juan if your dates are fixed — just plan around the conditions.
Average high
31°C / 88°F
Average low
25°C / 77°F
Rain days
~19
Precipitation
108 mm
What to pack for San Juan in August
- Light, breathable clothing — linen and technical fabrics earn their keep
- High-SPF sunscreen, sunglasses, and a refillable water bottle
- Rain gear is non-negotiable — expect rain on roughly 19 days
- Comfortable walking shoes — every guide on this site assumes you'll use them
August against the rest of the year
Warmest in San Juan: Jun (32°C / 90°F) · Coolest: Jan (28°C / 82°F) · Wettest: Sep (~22 rain days)
28°
22°
Jan
28°
22°
Feb
28°
22°
Mar
29°
23°
Apr
31°
24°
May
32°
25°
Jun
31°
25°
Jul
31°
25°
Aug
31°
25°
Sep
30°
25°
Oct
29°
24°
Nov
28°
23°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)