Riachão climate — normals and trends
Riachão (Brazil) has a tropical savanna climate (Aw) under the Köppen-Geiger classification. Its mean annual temperature is 26.1 °C and it receives 1,586 mm of precipitation per year.
These figures are normals computed over 86 complete calendar years, from 1940 to 2025, using ERA5 reanalysis data from the Copernicus programme.
The warmest month is September (28.6 °C on average) and the coldest is January (24.6 °C). Rainfall peaks in January.
Riachão averages 0 frost days, 238 hot days (≥ 30 °C) and 165 rainy days per year.
Riachão has warmed by +0.7 °C between 1940 and 2025, or +0.08 °C per decade. This trend is statistically significant.
The hottest day of the period reached 39.1 °C (on 24 October 2017) and the coldest 16.5 °C (on 29 July 2020).
Data from ERA5 reanalysis (Copernicus Climate Change Service), redistributed under a CC-BY 4.0 licence. Normals are recomputed whenever the archive is updated.
Climate normals · ERA5
RiachãoMaranhão
- coords
- -7.36°, -46.62°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
26.1°C
Average daily high
31.1°C
Average daily low
21.8°C
Annual rainfall
1,586mm
Sunshine / day
10.5h
Mean relative humidity
68%
Average peak wind
13.3km/h
Seasonal range
4.0°C
Frost days (< 0 °C)
0 d/yr
Hot days (≥ 30 °C)
238 d/yr
Rainy days (≥ 1 mm)
165 d/yr
Annual snowfall
0.0 cm
Average feels-like high
34.4 °C
Average feels-like low
24.0 °C
Average peak gust
33.5 km/h
Tropical nights (≥ 20 °C)
349 d/yr
Solar radiation
19.7 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+0.7 °C
since 1940
+0.1 °C per decade · r² = 0.12 · p = < 0.001
Trend fitted by linear regression (ordinary least squares) on annual means. A trend is shown only when it is statistically significant (p < 0.05).
A climograph overlays rainfall (bars) and temperature (line): the standard reading in climatology, where you can see at a glance whether the warm season is also the dry one.
Records for the period
Hottest day
39.1 °C
24 October 2017
Coldest day
16.5 °C
29 July 2020
Wettest day
185 mm
4 March 1978
Windiest day
30.2 km/h
14 November 1985
Strongest gust
60.8 km/h
11 October 1960
Hottest feels-like
42.6 °C
4 October 2015
Coldest feels-like
14.8 °C
28 July 2025
Sunniest day
12.2 h
14 January 1956
Normals computed over complete calendar years 1940–2025.
A specific year
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Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 29.3 °C | +0.2 °C | 389 mm | +102 mm |
| Feb | 29.7 °C | +0.6 °C | 155 mm | -115 mm |
| Mar | 30.1 °C | +1.0 °C | 208 mm | -76 mm |
| Apr | 31.1 °C | +1.5 °C | 60 mm | -109 mm |
| May | 33.0 °C | +2.2 °C | 7 mm | -42 mm |
| Jun | 33.0 °C | +1.2 °C | 2 mm | -6 mm |
| Jul | 33.9 °C | +1.5 °C | 1 mm | -1 mm |
| Aug | 34.7 °C | +0.8 °C | 3 mm | -1 mm |
| Sep | 36.0 °C | +1.5 °C | 2 mm | -17 mm |
| Oct | 34.8 °C | +1.9 °C | 18 mm | -68 mm |
| Nov | 31.7 °C | +0.9 °C | 169 mm | -9 mm |
| Dec | 29.4 °C | -0.3 °C | 240 mm | +8 mm |
The year's extremes
What was the weather like that day?
Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.
Frequently asked questions
What is the climate of Riachão?
Riachão has a tropical savanna climate (Köppen Aw). Over 1940-2025, the average annual temperature is 26.1 °C and it receives 1,586 mm of precipitation per year.
What is the hottest day ever recorded in Riachão?
The hottest day measured in Riachão between 1940 and 2025 was 24 October 2017, reaching 39.1 °C.
What is the coldest day in Riachão?
The coldest day measured in Riachão between 1940 and 2025 was 29 July 2020, at 16.5 °C.
Does it snow in Riachão?
Almost never: Riachão sees virtually no snow, with about 0 frost days per year.
Has the climate of Riachão warmed?
Yes: Riachão warmed by +0.7 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Riachão?
The wettest day measured in Riachão between 1940 and 2025 was 4 March 1978, with 185 mm of rain in 24 hours.
What was the windiest day in Riachão?
The windiest day measured in Riachão between 1940 and 2025 was 14 November 1985, with winds reaching 30.2 km/h.
What is the warmest month in Riachão?
The warmest month in Riachão is September (28.6 °C on average); the coldest is January (24.6 °C).
How much does it rain in Riachão?
Riachão receives on average 1,586 mm of precipitation per year, spread over about 165 rainy days.
Is it sunny in Riachão?
Riachão gets on average 10.5 hours of sunshine per day, roughly 3,833 hours per year over 1940-2025.
Are there tropical nights in Riachão?
Yes: Riachão has on average 349 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Riachão?
In Riachão, between 1940 and 2025, the highest apparent temperature reached 42.6 °C on 4 October 2015, and the lowest was 14.8 °C on 28 July 2025.
Compare Riachão with another city
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Nearby cities
The climate around Riachão