São Sebastião do Caí in Summer
In summer (December, January and February), São Sebastião do Caí sees average daytime highs around 28°C and overnight lows near 18°C, with 571 mm of rain over about 49 wet days across the season. It is the warmest season of the year and the wettest season of the year.
Across summer, daytime highs hold fairly steady around 28°C. The sky is clear or mostly clear about 29% of the time across summer, and the air most often feels muggy.
Summer is São Sebastião do Caí's weakest season of the year to visit on our travel score. For the whole year in context, see São Sebastião do Caí's year-round climate.
- Avg daytime high
- 28°C
- warmest season of the year
- Avg overnight low
- 18°C
- Rainfall
- 571 mm
- 49 wet days
- Avg wind
- 8 km/h
- Travel score
- 5.0
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in São Sebastião do Caí in Summer
Across summer, daytime highs hold fairly steady around 28°C.
A typical summer day in São Sebastião do Caí reaches about 28°C and drops to 18°C overnight. The warmest of the three months is January, the coolest December.
São Sebastião do Caí 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 | 29° / 19° | 209 | 17.6 | 13.7 | 4.7 |
| Feb | 28° / 19° | 180 | 16.6 | 13.1 | 4.8 |
| Mar | 27° / 18° | 154 | 15.2 | 12.2 | 5.8 |
| Apr | 24° / 15° | 142 | 11.2 | 11.3 | 6.6 |
| May | 21° / 12° | 136 | 10.4 | 10.5 | 6.4 |
| Jun | 19° / 10° | 144 | 10.3 | 10.1 | 6.0 |
| Jul | 19° / 9° | 180 | 10.8 | 10.3 | 6.0 |
| Aug | 21° / 11° | 145 | 10.7 | 10.9 | 6.4 |
| Sep | 22° / 12° | 178 | 12.5 | 11.8 | 6.1 |
| Oct | 24° / 14° | 216 | 14.8 | 12.7 | 6.0 |
| Nov | 26° / 16° | 164 | 12.8 | 13.5 | 6.2 |
| Dec | 28° / 18° | 182 | 15.1 | 13.9 | 5.4 |
Cloud cover in Summer
The sky is clear or mostly clear about 29% of the time across summer.
Chance of precipitation in Summer
São Sebastião do Caí gets around 571 mm of rain over 49 wet days across summer. The line is the day-by-day chance of measurable precipitation.
Humidity in Summer
Most of summer feels muggy — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Summer
Winds average 8 km/h across summer.
Sunrise & sunset in Summer
Daylight runs from about 13 h 48 min in early December to 12 h 42 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 6.1 kWh/m².
Is summer a good time to visit São Sebastião do Caí?
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 reasonable time to visit São Sebastião do Caí for sightseeing.
What to pack for São Sebastião do Caí in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, São Sebastião do Caí sees daytime highs around 28°C and nights near 18°C. Pack light clothes, rain gear and sun protection. About 49 days see rain.
UV index in São Sebastião do Caí 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 São Sebastião do Caí peaks around January 16 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 4 (moderate).
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) | 13 | 12 | 10 | 8 | 5 | 4 | 4 | 5 | 8 | 8 | 12 | 13 |
| Level | Extreme | Extreme | Very high | Very high | Moderate | Moderate | Moderate | High | Very high | Very high | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 13 | Extreme |
| Feb | 12 | Extreme |
| Mar | 10 | Very high |
| Apr | 8 | Very high |
| May | 5 | Moderate |
| Jun | 4 | Moderate |
| Jul | 4 | Moderate |
| Aug | 5 | High |
| Sep | 8 | Very high |
| Oct | 8 | Very high |
| Nov | 12 | Extreme |
| Dec | 13 | Extreme |
Air quality in São Sebastião do Caí 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 São Sebastião do Caí is worst in September — around 17 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (December, 10 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) | 10 | 10 | 10 | 12 | 12 | 11 | 13 | 16 | 17 | 12 | 11 | 10 |
| Level | Good | Good | Good | Good | Good | Good | Moderate | Moderate | Moderate | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 10 | Good |
| Feb | 10 | Good |
| Mar | 10 | Good |
| Apr | 12 | Good |
| May | 12 | Good |
| Jun | 11 | Good |
| Jul | 13 | Moderate |
| Aug | 16 | Moderate |
| Sep | 17 | Moderate |
| Oct | 12 | Good |
| Nov | 11 | Good |
| Dec | 10 | Good |
Where is São Sebastião do Caí?
São Sebastião do Caí sits at 29.6°S, 51.4°W, 16 m above sea level, in Brazil. The nearest listed city is Montenegro, 14 km away.
Topography around São Sebastião do Caí
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of São Sebastião do Caí.
Within 3 km, the terrain around São Sebastião do Caí has only modest variations in elevation — a maximum elevation change of 107 m around an average of 32 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 512 m; within 80 km, large variations in elevation — a maximum elevation change of 988 m.
The land around São Sebastião do Caí is covered by trees (69%) within 3 km, trees (73%) within 16 km, and trees (62%) within 80 km.
Brazil travel facts
- Travel advisory
- Level 2
- Exercise Increased Caution
- Power plugs
- Type C / N
- 127 / 220 V · 60 Hz
- Prices
- ≈ 46% of US
- price level, 2025
- GDP per capita
- $10,713
- 2025
- Happiness
- 6.6 / 10
- World Happiness, 2025
- Safe drinking water
- 89%
- of population, 2024
- Homicide rate
- 19.3
- per 100k, 2023
- Road deaths
- 16
- per 100k/yr, 2019
- Income group
- Upper middle
- World Bank
- English
- Low
- EF EPI 482
- 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 São Sebastião do Caí (-29.5867°, -51.3756°, elevation 16 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.