San Juan in Summer
In summer (December, January and February), San Juan sees average daytime highs around 30°C and overnight lows near 24°C, with 748 mm of rain over about 78 wet days across the season. It is the 2nd-warmest season and the 2nd-wettest season.
Across summer, daytime highs hold fairly steady around 30°C. The sky is clear or mostly clear about 2% of the time across summer, and the air most often feels oppressive.
Summer is San Juan's weakest season of the year to visit on our travel score. San Juan has little temperature swing across the year, so its calendar seasons blur — the season framing matters less here than for a place with four distinct seasons. For the whole year in context, see San Juan's year-round climate.
- Avg daytime high
- 30°C
- 2nd-warmest season
- Avg overnight low
- 24°C
- Rainfall
- 748 mm
- 78 wet days
- Avg wind
- 4 km/h
- Travel score
- 2.9
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in San Juan in Summer
Across summer, daytime highs hold fairly steady around 30°C.
A typical summer day in San Juan reaches about 30°C and drops to 24°C overnight. The warmest of the three months is December, the coolest December.
How summer really feels in San Juan
Once humidity and wind are folded in, summer brings about 90 days that feel above 32°C and 0 that feel at or below 0°C.
The story in summer is heat — humidity pushes the afternoon "feels like" well above the raw temperature.
San Juan weather by month
How the three summer months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|
| Jan | 30° / 24° | 252 | 25.9 | 12.2 | 3.0 |
| Feb | 30° / 24° | 233 | 24.5 | 12.1 | 2.9 |
| Mar | 30° / 24° | 304 | 28.4 | 12 | 2.8 |
| Apr | 30° / 23° | 294 | 27.3 | 11.9 | 2.9 |
| May | 29° / 23° | 271 | 26.7 | 11.8 | 3.2 |
| Jun | 29° / 23° | 219 | 25 | 11.8 | 3.4 |
| Jul | 29° / 22° | 166 | 23.3 | 11.8 | 3.8 |
| Aug | 30° / 22° | 154 | 21.8 | 11.9 | 3.6 |
| Sep | 31° / 23° | 179 | 23.5 | 12 | 3.2 |
| Oct | 31° / 23° | 201 | 25.9 | 12.1 | 2.9 |
| Nov | 30° / 24° | 235 | 25.8 | 12.2 | 2.9 |
| Dec | 30° / 24° | 263 | 27.2 | 12.2 | 2.9 |
Cloud cover in Summer
The sky is clear or mostly clear about 2% of the time across summer.
Chance of precipitation in Summer
San Juan gets around 748 mm of rain over 78 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels oppressive — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 4 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 12 h 12 min in early December to 12 h 06 min by late February. The lit band spans sunrise to sunset each day.
Solar energy in Summer
Average shortwave solar energy reaching the ground each day across summer, about 4.6 kWh/m².
Is summer a good time to visit San Juan?
Our two travel scores rate summer for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
summer is a weaker month for outdoor sightseeing in San Juan.
What to pack for San Juan in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, San Juan sees daytime highs around 30°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 78 days see rain.
UV index in San Juan in Summer
Clear-sky midday UV across summer averages around 14 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in San Juan peaks around February 13 at about 16 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near August 14 at about 9 (very high).
The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 15 | 16 | 15 | 12 | 13 | 11 | 10 | 9 | 12 | 12 | 12 | 12 |
| Level | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | Extreme | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 15 | Extreme |
| Feb | 16 | Extreme |
| Mar | 15 | Extreme |
| Apr | 12 | Extreme |
| May | 13 | Extreme |
| Jun | 11 | Extreme |
| Jul | 10 | Extreme |
| Aug | 9 | Very high |
| Sep | 12 | Extreme |
| Oct | 12 | Extreme |
| Nov | 12 | Extreme |
| Dec | 12 | Extreme |
Air quality in San Juan in Summer
Average fine-particle pollution (PM2.5) through the year — so you can see where summer falls, not just the annual average.
Air quality in San Juan is worst in March — around 15 µg/m³ PM2.5 (moderate), about 1.7× the cleanest month (June, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 14 | 15 | 15 | 12 | 10 | 9 | 10 | 13 | 15 | 10 | 11 | 12 |
| Level | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Moderate | Moderate | Good | Good | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 14 | Moderate |
| Feb | 15 | Moderate |
| Mar | 15 | Moderate |
| Apr | 12 | Moderate |
| May | 10 | Good |
| Jun | 9 | Good |
| Jul | 10 | Good |
| Aug | 13 | Moderate |
| Sep | 15 | Moderate |
| Oct | 10 | Good |
| Nov | 11 | Good |
| Dec | 12 | Moderate |
Where is San Juan?
San Juan sits at 3.8°S, 73.3°W, 99 m above sea level, in Peru. The nearest listed city is Belen, 4.0 km away.
Topography around San Juan
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Juan.
Within 3 km, the terrain around San Juan has only modest variations in elevation — a maximum elevation change of 37 m around an average of 94 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 78 m; within 80 km, only modest variations in elevation — a maximum elevation change of 116 m.
The land around San Juan is covered by trees (53%) and artificial surfaces (30%) within 3 km, trees (79%) within 16 km, and trees (96%) within 80 km.
Peru travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type A / B / C
- 220 V · 60 Hz
- Prices
- ≈ 51% of US
- price level, 2025
- GDP per capita
- $9,684
- 2025
- Happiness
- 6.0 / 10
- World Happiness, 2025
- Safe drinking water
- 49%
- of population, 2024
- Homicide rate
- 8.6
- per 100k, 2021
- Road deaths
- 13.6
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Moderate
- EF EPI 519
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for San Juan (-3.7761°, -73.2814°, elevation 99 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.