São Mateus do Maranhão in Summer
In summer (December, January and February), São Mateus do Maranhão sees average daytime highs around 32°C and overnight lows near 24°C, with 618 mm of rain over about 64 wet days across the season. It is the 3rd-warmest season and the 2nd-wettest season.
Over the season highs ease from about 35°C in early December to 31°C by late February. The sky is clear or mostly clear about 9% of the time across summer, and the air most often feels oppressive.
Summer is São Mateus do Maranhão's weakest season of the year to visit on our travel score. For the whole year in context, see São Mateus do Maranhão's year-round climate.
- Avg daytime high
- 32°C
- 3rd-warmest season
- Avg overnight low
- 24°C
- Rainfall
- 618 mm
- 64 wet days
- Avg wind
- 7 km/h
- Travel score
- 2.6
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in São Mateus do Maranhão in Summer
Over the season highs ease from about 35°C in early December to 31°C by late February.
A typical summer day in São Mateus do Maranhão reaches about 32°C and drops to 24°C overnight. The warmest of the three months is December, the coolest February.
How summer really feels in São Mateus do Maranhão
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.
São Mateus do Maranhão 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 | 32° / 24° | 242 | 24.3 | 12.2 | 2.6 |
| Feb | 31° / 24° | 263 | 25 | 12.1 | 2.5 |
| Mar | 31° / 24° | 312 | 28.6 | 12 | 2.5 |
| Apr | 31° / 24° | 277 | 27.1 | 11.9 | 2.6 |
| May | 31° / 24° | 134 | 19.2 | 11.8 | 3.4 |
| Jun | 32° / 23° | 37 | 7.6 | 11.8 | 4.4 |
| Jul | 33° / 23° | 18 | 3.6 | 11.8 | 4.3 |
| Aug | 34° / 24° | 5 | 1.2 | 11.9 | 3.7 |
| Sep | 35° / 25° | 6 | 1.1 | 12 | 3.0 |
| Oct | 36° / 25° | 13 | 3.1 | 12.1 | 2.6 |
| Nov | 35° / 25° | 44 | 6.8 | 12.2 | 2.6 |
| Dec | 34° / 25° | 113 | 14.3 | 12.2 | 2.6 |
Cloud cover in Summer
The sky is clear or mostly clear about 9% of the time across summer.
Chance of precipitation in Summer
São Mateus do Maranhão gets around 618 mm of rain over 64 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 7 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 5.0 kWh/m².
Hazard calendar for São Mateus do Maranhão
In summer, São Mateus do Maranhão overlaps its monsoon season. The full year is below, with each hazard's peak months called out.
São Mateus do Maranhão's monsoon runs January–April, when most of the year's rain falls.
Is summer a good time to visit São Mateus do Maranhão?
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 São Mateus do Maranhão.
What to pack for São Mateus do Maranhão in Summer
From summer's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In summer, São Mateus do Maranhão sees daytime highs around 32°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 64 days see rain.
UV index in São Mateus do Maranhão 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 Mateus do Maranhão peaks around March 16 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 24 at about 10 (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) | 13 | 14 | 15 | 14 | 11 | 10 | 10 | 10 | 12 | 12 | 11 | 11 |
| Level | Extreme | Extreme | Extreme | Extreme | Extreme | Extreme | Very high | Very high | Extreme | Extreme | Extreme | Extreme |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 13 | Extreme |
| Feb | 14 | Extreme |
| Mar | 15 | Extreme |
| Apr | 14 | Extreme |
| May | 11 | Extreme |
| Jun | 10 | Extreme |
| Jul | 10 | Very high |
| Aug | 10 | Very high |
| Sep | 12 | Extreme |
| Oct | 12 | Extreme |
| Nov | 11 | Extreme |
| Dec | 11 | Extreme |
Air quality in São Mateus do Maranhão 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 Mateus do Maranhão is worst in October — around 25 µg/m³ PM2.5 (moderate), about 3.0× the cleanest month (June, 8 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 | 16 | 15 | 13 | 10 | 8 | 9 | 12 | 16 | 25 | 23 | 17 |
| Level | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good | Moderate | Moderate | Moderate | Moderate |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 14 | Moderate |
| Feb | 16 | Moderate |
| Mar | 15 | Moderate |
| Apr | 13 | Moderate |
| May | 10 | Good |
| Jun | 8 | Good |
| Jul | 9 | Good |
| Aug | 12 | Good |
| Sep | 16 | Moderate |
| Oct | 25 | Moderate |
| Nov | 23 | Moderate |
| Dec | 17 | Moderate |
Where is São Mateus do Maranhão?
São Mateus do Maranhão sits at 4.0°S, 44.5°W, 47 m above sea level, in Brazil. The nearest listed city is Alto Alegre do Maranhão, 19 km away.
Topography around São Mateus do Maranhão
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of São Mateus do Maranhão.
Within 3 km, the terrain around São Mateus do Maranhão has only modest variations in elevation — a maximum elevation change of 28 m around an average of 42 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 76 m; within 80 km, only modest variations in elevation — a maximum elevation change of 174 m.
The land around São Mateus do Maranhão is covered by grassland (44%) and trees (29%) within 3 km, grassland (50%) and trees (31%) within 16 km, and trees (47%) and grassland (46%) 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 Mateus do Maranhão (-4.0417°, -44.475°, elevation 47 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.