Oeiras climate — normals and trends
Oeiras (Brazil) has a hot semi-arid climate (BSh) under the Köppen-Geiger classification. Its mean annual temperature is 28.2 °C and it receives 781 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 October (31.1 °C on average) and the coldest is March (26.2 °C). Rainfall peaks in March.
Oeiras averages 0 frost days, 315 hot days (≥ 30 °C) and 99 rainy days per year.
Oeiras has warmed by +1.0 °C between 1940 and 2025, or +0.12 °C per decade. This trend is statistically significant.
The hottest day of the period reached 41.0 °C (on 20 November 2005) and the coldest 18.9 °C (on 4 July 1974).
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
OeirasPiauí
- coords
- -7.03°, -42.13°
- period
- 1940–2025 · 86 yrs
Mean daily temperature
28.2°C
Average daily high
33.1°C
Average daily low
24.0°C
Annual rainfall
781mm
Sunshine / day
10.8h
Mean relative humidity
58%
Average peak wind
14.5km/h
Seasonal range
4.9°C
Frost days (< 0 °C)
0 d/yr
Hot days (≥ 30 °C)
315 d/yr
Rainy days (≥ 1 mm)
99 d/yr
Annual snowfall
0.0 cm
Average feels-like high
36.1 °C
Average feels-like low
25.6 °C
Average peak gust
34.4 km/h
Tropical nights (≥ 20 °C)
364 d/yr
Solar radiation
20.3 MJ/m²
Has the climate changed?
One stripe per year, 1940 to 2025
+1.0 °C
since 1940
+0.1 °C per decade · r² = 0.13 · 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
41.0 °C
20 November 2005
Coldest day
18.9 °C
4 July 1974
Wettest day
142 mm
5 April 1995
Windiest day
33.1 km/h
4 July 2017
Strongest gust
68.8 km/h
4 July 2017
Hottest feels-like
45.6 °C
31 October 2012
Coldest feels-like
17.7 °C
2 July 1974
Sunniest day
12.4 h
30 November 1945
Normals computed over complete calendar years 1940–2025.
A specific year
Pick a year and see how it compares to normal — warmer, drier or more extreme than usual?
Across the whole year
Month by month
| High | vs. normal | Precipitation | vs. normal | |
|---|---|---|---|---|
| Jan | 31.1 °C | -0.5 °C | 176 mm | +19 mm |
| Feb | 33.2 °C | +2.3 °C | 18 mm | -143 mm |
| Mar | 32.8 °C | +2.2 °C | 32 mm | -152 mm |
| Apr | 34.0 °C | +2.9 °C | 28 mm | -76 mm |
| May | 33.9 °C | +1.6 °C | 1 mm | -26 mm |
| Jun | 34.1 °C | +1.3 °C | 0 mm | -3 mm |
| Jul | 34.9 °C | +1.8 °C | 0 mm | -2 mm |
| Aug | 35.7 °C | +1.2 °C | 0 mm | 0 mm |
| Sep | 36.8 °C | +0.9 °C | 0 mm | -2 mm |
| Oct | 36.9 °C | +0.6 °C | 5 mm | -8 mm |
| Nov | 36.0 °C | +1.0 °C | 23 mm | -21 mm |
| Dec | 33.2 °C | -0.2 °C | 37 mm | -47 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 Oeiras?
Oeiras has a hot semi-arid climate (Köppen BSh). Over 1940-2025, the average annual temperature is 28.2 °C and it receives 781 mm of precipitation per year.
What is the hottest day ever recorded in Oeiras?
The hottest day measured in Oeiras between 1940 and 2025 was 20 November 2005, reaching 41.0 °C.
What is the coldest day in Oeiras?
The coldest day measured in Oeiras between 1940 and 2025 was 4 July 1974, at 18.9 °C.
Does it snow in Oeiras?
Almost never: Oeiras sees virtually no snow, with about 0 frost days per year.
Has the climate of Oeiras warmed?
Yes: Oeiras warmed by +1.0 °C between 1940 and 2025, a statistically significant trend.
What is the wettest day in Oeiras?
The wettest day measured in Oeiras between 1940 and 2025 was 5 April 1995, with 142 mm of rain in 24 hours.
What was the windiest day in Oeiras?
The windiest day measured in Oeiras between 1940 and 2025 was 4 July 2017, with winds reaching 33.1 km/h.
What is the warmest month in Oeiras?
The warmest month in Oeiras is October (31.1 °C on average); the coldest is March (26.2 °C).
How much does it rain in Oeiras?
Oeiras receives on average 781 mm of precipitation per year, spread over about 99 rainy days.
Is it sunny in Oeiras?
Oeiras gets on average 10.8 hours of sunshine per day, roughly 3,942 hours per year over 1940-2025.
Are there tropical nights in Oeiras?
Yes: Oeiras has on average 364 tropical nights per year (temperature staying above 20 °C), over 1940-2025.
What was the most extreme apparent temperature in Oeiras?
In Oeiras, between 1940 and 2025, the highest apparent temperature reached 45.6 °C on 31 October 2012, and the lowest was 17.7 °C on 2 July 1974.
Compare Oeiras with another city
Pick a second city: its normals will be set against these, indicator by indicator.
Nearby cities
The climate around Oeiras