San Antonio in Summer
In summer (December, January and February), San Antonio sees average daytime highs around 20°C and overnight lows near 13°C, with 5 mm of rain over about 1 wet days across the season. It is the warmest season of the year and the driest season of the year.
Across summer, daytime highs hold fairly steady around 20°C. The sky is clear or mostly clear about 85% of the time across summer, and the air most often feels dry.
Summer is San Antonio's best season of the year to visit on our travel score. For the whole year in context, see San Antonio's year-round climate.
- Avg daytime high
- 20°C
- warmest season of the year
- Avg overnight low
- 13°C
- Rainfall
- 5 mm
- 1 wet days
- Avg wind
- 11 km/h
- Travel score
- 8.6
- best season of the year
- Months
- Dec · Jan · Feb
Temperature in San Antonio in Summer
Across summer, daytime highs hold fairly steady around 20°C.
A typical summer day in San Antonio reaches about 20°C and drops to 13°C overnight. The warmest of the three months is January, the coolest December.
San Antonio 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 | 21° / 14° | 0 | 0.1 | 14 | 8.8 |
| Feb | 21° / 14° | 2 | 0.3 | 13.2 | 8.7 |
| Mar | 20° / 12° | 4 | 0.7 | 12.3 | 8.4 |
| Apr | 18° / 10° | 18 | 2.2 | 11.2 | 7.2 |
| May | 16° / 9° | 61 | 4.7 | 10.3 | 5.5 |
| Jun | 14° / 8° | 122 | 7 | 9.8 | 4.3 |
| Jul | 13° / 7° | 67 | 5.5 | 10 | 4.2 |
| Aug | 14° / 7° | 59 | 5.1 | 10.8 | 4.6 |
| Sep | 15° / 8° | 28 | 3 | 11.8 | 5.5 |
| Oct | 17° / 10° | 14 | 1.8 | 12.8 | 6.7 |
| Nov | 18° / 11° | 4 | 0.7 | 13.7 | 7.9 |
| Dec | 20° / 12° | 3 | 0.4 | 14.2 | 8.4 |
Cloud cover in Summer
The sky is clear or mostly clear about 85% of the time across summer.
Chance of precipitation in Summer
San Antonio gets around 5 mm of rain over 1 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 11 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 14 h 06 min in early December to 12 h 48 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 8.5 kWh/m².
Is summer a good time to visit San Antonio?
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 one of the better times to visit San Antonio for general sightseeing.
What to pack for San Antonio in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, San Antonio sees daytime highs around 20°C and nights near 13°C. Pack sun protection.
Sea temperature near San Antonio in Summer
The nearest coast averages about 16°C across summer — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea offshore is warmest in February at about 16°C and coldest in August near 12°C.
The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 16 | 16 | 16 | 14 | 14 | 13 | 13 | 12 | 12 | 13 | 13 | 15 |
| Comfort | Cool | Cool | Cool | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 16 | Cool |
| Feb | 16 | Cool |
| Mar | 16 | Cool |
| Apr | 14 | Bracing |
| May | 14 | Bracing |
| Jun | 13 | Bracing |
| Jul | 13 | Bracing |
| Aug | 12 | Bracing |
| Sep | 12 | Bracing |
| Oct | 13 | Bracing |
| Nov | 13 | Bracing |
| Dec | 15 | Bracing |
UV index in San Antonio in Summer
Clear-sky midday UV across summer averages around 13 (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 Antonio peaks around January 17 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 19 at about 3 (moderate).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 10 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 14 | 12 | 10 | 5 | 3 | 3 | 3 | 4 | 6 | 9 | 11 | 12 |
| Level | Extreme | Extreme | Very high | High | Moderate | Moderate | Moderate | Moderate | High | Very high | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 14 | Extreme |
| Feb | 12 | Extreme |
| Mar | 10 | Very high |
| Apr | 5 | High |
| May | 3 | Moderate |
| Jun | 3 | Moderate |
| Jul | 3 | Moderate |
| Aug | 4 | Moderate |
| Sep | 6 | High |
| Oct | 9 | Very high |
| Nov | 11 | Extreme |
| Dec | 12 | Extreme |
Air quality in San Antonio 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 Antonio is worst in July — around 88 µg/m³ PM2.5 (unhealthy), about 2.5× the cleanest month (February, 35 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) | 45 | 35 | 40 | 58 | 83 | 85 | 88 | 77 | 64 | 45 | 37 | 38 |
| Level | Poor | Moderate | Poor | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Unhealthy | Poor | Poor | Poor |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 45 | Poor |
| Feb | 35 | Moderate |
| Mar | 40 | Poor |
| Apr | 58 | Unhealthy |
| May | 83 | Unhealthy |
| Jun | 85 | Unhealthy |
| Jul | 88 | Unhealthy |
| Aug | 77 | Unhealthy |
| Sep | 64 | Unhealthy |
| Oct | 45 | Poor |
| Nov | 37 | Poor |
| Dec | 38 | Poor |
Where is San Antonio?
San Antonio sits at 33.6°S, 71.6°W, 39 m above sea level, in Chile. The nearest listed city is Cartagena, 5.0 km away.
Topography around San Antonio
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of San Antonio.
Within 3 km, the terrain around San Antonio has only modest variations in elevation — a maximum elevation change of 212 m around an average of 54 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 488 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,259 m.
The land around San Antonio is covered by artificial surfaces (38%) and water (23%) within 3 km, water (40%) and grassland (24%) within 16 km, and water (29%) and grassland (22%) within 80 km.
Chile travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / F / L
- 220 V · 50 Hz
- Prices
- ≈ 48% of US
- price level, 2025
- GDP per capita
- $17,995
- 2025
- Happiness
- 6.3 / 10
- World Happiness, 2025
- Safe drinking water
- 98%
- of population, 2024
- Homicide rate
- 6.3
- per 100k, 2023
- Road deaths
- 14.9
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Moderate
- EF EPI 517
- 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 Antonio (-33.5947°, -71.6075°, elevation 39 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.