União climate — normals and trends

Q: What is the climate of União?

União has a tropical savanna climate (Köppen Aw). Over 1940-2025, the average annual temperature is 28.0 °C and it receives 1,509 mm of precipitation per year.

Q: What is the hottest day ever recorded in União?

The hottest day measured in União between 1940 and 2025 was 20 November 2005, reaching 41.3 °C.

Q: What is the coldest day in União?

The coldest day measured in União between 1940 and 2025 was 26 July 2024, at 17.9 °C.

Q: Does it snow in União?

Almost never: União sees virtually no snow, with about 0 frost days per year.

Q: Has the climate of União warmed?

Yes: União warmed by +0.8 °C between 1940 and 2025, a statistically significant trend.

Q: What is the wettest day in União?

The wettest day measured in União between 1940 and 2025 was 9 April 1977, with 242 mm of rain in 24 hours.

Q: What was the windiest day in União?

The windiest day measured in União between 1940 and 2025 was 5 July 2017, with winds reaching 26.5 km/h.

Q: What is the warmest month in União?

The warmest month in União is October (30.4 °C on average); the coldest is March (26.0 °C).

Q: How much does it rain in União?

União receives on average 1,509 mm of precipitation per year, spread over about 137 rainy days.

Q: Is it sunny in União?

União gets on average 10.8 hours of sunshine per day, roughly 3,942 hours per year over 1940-2025.

União (Brazil) has a tropical savanna climate (Aw) under the Köppen-Geiger classification. Its mean annual temperature is 28.0 °C and it receives 1,509 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 (30.4 °C on average) and the coldest is March (26.0 °C). Rainfall peaks in March.

União averages 0 frost days, 317 hot days (≥ 30 °C) and 137 rainy days per year.

União has warmed by +0.8 °C between 1940 and 2025, or +0.10 °C per decade. This trend is statistically significant.

The hottest day of the period reached 41.3 °C (on 20 November 2005) and the coldest 17.9 °C (on 26 July 2024).

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

UniãoPiauí

coords: -4.59°, -42.86°
period: 1940–2025 · 86 yrs

AwTropical savannaWarmest monthOctoberColdest monthMarchWettest monthMarchDriest monthAugust

Mean daily temperature

28.0°C

Average daily high

33.3°C

Average daily low

23.5°C

Annual rainfall

1,509mm

Sunshine / day

10.8h

Mean relative humidity

69%

Average peak wind

12.4km/h

Seasonal range

4.4°C

Frost days (< 0 °C)

0 d/yr

Hot days (≥ 30 °C)

317 d/yr

Rainy days (≥ 1 mm)

137 d/yr

Annual snowfall

0.0 cm

Average feels-like high

37.3 °C

Average feels-like low

27.1 °C

Average peak gust

32.2 km/h

Tropical nights (≥ 20 °C)

364 d/yr

Solar radiation

20.2 MJ/m²

Has the climate changed?

One stripe per year, 1940 to 2025

+0.8 °C

since 1940

+0.1 °C per decade · r² = 0.15 · p = < 0.001

19402025

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

41.3 °C

20 November 2005

Coldest day

17.9 °C

26 July 2024

Wettest day

242 mm

9 April 1977

Windiest day

26.5 km/h

5 July 2017

Strongest gust

57.2 km/h

17 July 1947

Hottest feels-like

44.7 °C

14 October 2018

Coldest feels-like

18.7 °C

3 August 2001

Sunniest day

12.1 h

14 November 1940

Year	Hottest day	Coldest day	Annual mean	Rainfall	Hot days
2025	39.5 °C14 October 2025	20.6 °C18 July 2025	28.7 °C	1,070 mm	344
2024	38.7 °C26 October 2024	17.9 °C26 July 2024	28.3 °C	1,113 mm	356
2023	39.3 °C28 October 2023	20.1 °C18 August 2023	28.0 °C	1,366 mm	338
2022	37.8 °C21 October 2022	19.5 °C22 August 2022	27.5 °C	1,499 mm	338
2021	38.0 °C5 September 2021	20.1 °C26 July 2021	28.1 °C	1,297 mm	343
2020	38.8 °C21 October 2020	19.4 °C27 July 2020	28.1 °C	1,681 mm	343
2019	39.4 °C25 October 2019	20.3 °C19 July 2019	28.5 °C	1,458 mm	343
2018	39.2 °C28 October 2018	19.7 °C21 July 2018	28.2 °C	1,555 mm	329
2017	40.0 °C5 December 2017	20.4 °C19 July 2017	28.8 °C	1,394 mm	345
2016	40.6 °C25 November 2016	20.7 °C27 July 2016	29.2 °C	1,240 mm	352
2015	40.4 °C2 December 2015	21.0 °C18 June 2015	29.0 °C	956 mm	351
2014	39.1 °C19 October 2014	20.6 °C13 August 2014	28.5 °C	1,229 mm	346
2013	39.2 °C4 October 2013	22.4 °C21 June 2013	29.1 °C	1,184 mm	355
2012	41.0 °C24 October 2012	21.1 °C30 July 2012	29.5 °C	1,162 mm	359
2011	39.8 °C25 September 2011	21.2 °C9 August 2011	28.4 °C	1,742 mm	332
2010	40.4 °C4 October 2010	19.6 °C27 June 2010	29.2 °C	1,053 mm	355
2009	39.3 °C29 November 2009	21.2 °C25 July 2009	28.1 °C	2,380 mm	321
2008	39.5 °C27 October 2008	20.9 °C7 August 2008	28.5 °C	1,398 mm	328
2007	39.9 °C26 January 2007	20.8 °C19 August 2007	28.9 °C	1,349 mm	345
2006	39.7 °C8 December 2006	20.4 °C2 June 2006	28.5 °C	2,088 mm	328
2005	41.3 °C20 November 2005	20.4 °C25 July 2005	28.8 °C	1,085 mm	348
2004	39.6 °C14 November 2004	20.1 °C9 June 2004	28.2 °C	1,645 mm	334
2003	38.5 °C23 October 2003	19.4 °C16 July 2003	28.1 °C	1,511 mm	336
2002	39.0 °C22 October 2002	21.5 °C22 January 2002	28.2 °C	1,568 mm	331
2001	39.5 °C23 December 2001	19.9 °C3 August 2001	27.7 °C	1,553 mm	330
2000	38.6 °C28 November 2000	20.5 °C5 June 2000	27.6 °C	1,498 mm	319
1999	39.2 °C10 November 1999	20.3 °C29 May 1999	27.5 °C	2,067 mm	316
1998	39.6 °C7 October 1998	21.6 °C5 July 1998	28.7 °C	1,221 mm	349
1997	39.4 °C6 October 1997	20.1 °C16 June 1997	28.0 °C	1,294 mm	334
1996	39.0 °C4 November 1996	19.8 °C26 June 1996	27.8 °C	2,373 mm	323
1995	38.8 °C14 November 1995	20.5 °C13 July 1995	27.5 °C	2,116 mm	315
1994	38.2 °C23 October 1994	20.3 °C19 July 1994	27.8 °C	1,918 mm	323
1993	39.7 °C23 December 1993	20.9 °C18 July 1993	28.7 °C	1,548 mm	345
1992	39.4 °C6 January 1992	20.3 °C22 July 1992	28.8 °C	919 mm	343
1991	38.6 °C22 November 1991	20.7 °C13 August 1991	28.0 °C	1,454 mm	335
1990	38.3 °C13 October 1990	21.3 °C28 July 1990	28.2 °C	910 mm	346
1989	38.7 °C29 October 1989	20.8 °C29 March 1989	27.5 °C	1,914 mm	305
1988	39.4 °C26 November 1988	20.2 °C3 August 1988	27.8 °C	1,915 mm	322
1987	40.2 °C28 November 1987	21.3 °C27 June 1987	28.8 °C	1,368 mm	338
1986	39.1 °C18 December 1986	20.2 °C16 June 1986	27.4 °C	2,070 mm	302
1985	38.9 °C22 October 1985	19.7 °C25 June 1985	27.0 °C	3,169 mm	268
1984	39.8 °C13 December 1984	19.9 °C27 July 1984	27.8 °C	1,883 mm	314
1983	38.8 °C3 November 1983	20.6 °C30 July 1983	29.0 °C	919 mm	348
1982	39.2 °C17 November 1982	20.6 °C25 August 1982	28.1 °C	1,395 mm	329
1981	39.5 °C26 October 1981	20.1 °C6 August 1981	28.4 °C	1,136 mm	338
1980	38.5 °C11 October 1980	21.3 °C19 January 1980	27.8 °C	1,637 mm	330
1979	38.7 °C2 November 1979	20.9 °C13 June 1979	27.6 °C	1,812 mm	332
1978	37.5 °C2 October 1978	20.4 °C7 June 1978	27.5 °C	1,597 mm	328
1977	39.2 °C22 November 1977	20.1 °C13 June 1977	27.4 °C	2,295 mm	308
1976	37.7 °C23 September 1976	20.2 °C21 July 1976	27.3 °C	1,518 mm	323
1975	37.6 °C14 October 1975	19.9 °C25 July 1975	27.0 °C	1,936 mm	299
1974	36.4 °C7 October 1974	19.1 °C12 June 1974	26.5 °C	2,785 mm	257
1973	37.6 °C15 November 1973	19.2 °C20 January 1973	27.1 °C	2,294 mm	310
1972	38.6 °C16 November 1972	20.5 °C16 June 1972	27.6 °C	1,696 mm	328
1971	37.5 °C11 October 1971	20.0 °C11 July 1971	26.9 °C	1,940 mm	293
1970	37.3 °C8 January 1970	21.3 °C8 June 1970	27.8 °C	1,219 mm	330
1969	37.7 °C6 October 1969	20.0 °C25 August 1969	27.7 °C	1,109 mm	333
1968	37.7 °C6 November 1968	20.0 °C9 June 1968	26.9 °C	1,689 mm	265
1967	37.3 °C4 December 1967	19.9 °C15 July 1967	26.9 °C	2,007 mm	279
1966	38.8 °C25 October 1966	20.9 °C10 August 1966	27.7 °C	1,559 mm	285
1965	39.5 °C17 November 1965	20.3 °C15 July 1965	28.0 °C	965 mm	297
1964	39.4 °C9 November 1964	20.6 °C3 June 1964	27.3 °C	1,559 mm	245
1963	39.9 °C17 October 1963	21.0 °C18 February 1963	27.8 °C	1,464 mm	264
1962	39.3 °C20 October 1962	20.2 °C20 June 1962	27.6 °C	1,085 mm	282
1961	39.7 °C24 November 1961	20.3 °C8 February 1961	27.7 °C	1,513 mm	268
1960	39.7 °C8 December 1960	20.9 °C10 May 1960	28.1 °C	1,568 mm	291
1959	39.2 °C1 December 1959	20.7 °C7 July 1959	27.8 °C	1,806 mm	267
1958	39.8 °C18 October 1958	21.4 °C4 March 1958	28.9 °C	833 mm	347
1957	39.4 °C5 November 1957	19.4 °C7 June 1957	28.0 °C	1,484 mm	272
1956	38.7 °C28 October 1956	20.4 °C17 April 1956	27.8 °C	1,194 mm	300
1955	39.3 °C10 January 1955	20.6 °C23 August 1955	27.7 °C	1,339 mm	281
1954	38.9 °C4 November 1954	20.9 °C5 August 1954	27.8 °C	1,167 mm	299
1953	39.4 °C7 December 1953	20.6 °C12 July 1953	27.9 °C	1,105 mm	300
1952	38.7 °C20 October 1952	19.9 °C23 June 1952	27.7 °C	1,574 mm	283
1951	39.1 °C8 December 1951	21.4 °C30 March 1951	28.4 °C	827 mm	330
1950	39.5 °C8 November 1950	20.4 °C27 May 1950	28.1 °C	1,452 mm	276
1949	39.8 °C10 October 1949	21.0 °C23 May 1949	27.7 °C	1,558 mm	275
1948	39.4 °C10 November 1948	21.0 °C22 January 1948	28.0 °C	1,311 mm	296
1947	39.1 °C10 October 1947	20.9 °C11 July 1947	27.4 °C	1,810 mm	289
1946	39.7 °C30 October 1946	20.7 °C3 July 1946	28.4 °C	944 mm	328
1945	39.7 °C10 November 1945	19.6 °C24 June 1945	27.6 °C	1,036 mm	292
1944	39.5 °C4 November 1944	20.7 °C17 March 1944	27.8 °C	1,898 mm	269
1943	39.5 °C24 October 1943	20.4 °C23 August 1943	27.2 °C	1,316 mm	274
1942	39.8 °C21 November 1942	21.0 °C29 May 1942	28.9 °C	863 mm	343
1941	39.9 °C23 October 1941	21.4 °C23 June 1941	29.0 °C	793 mm	343
1940	38.8 °C12 December 1940	20.1 °C6 July 1940	27.5 °C	1,531 mm	271

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?

Year

Across the whole year

Average daily high

34.2 °C

+0.9 °C

Hot days (≥ 30 °C)

344 d/yr

+27

Frost days (< 0 °C)

0 d/yr

Annual rainfall

1070 mm

-439 mm

Month by month

	High	vs. normal	Precipitation	vs. normal
Jan	32.2 °C	+0.2 °C	224 mm	+3 mm
Feb	31.7 °C	+0.6 °C	236 mm	-47 mm
Mar	31.2 °C	+0.7 °C	379 mm	+3 mm
Apr	32.0 °C	+1.5 °C	152 mm	-165 mm
May	32.8 °C	+1.7 °C	21 mm	-120 mm
Jun	33.4 °C	+1.1 °C	4 mm	-24 mm
Jul	34.5 °C	+1.0 °C	1 mm	-9 mm
Aug	35.8 °C	+0.9 °C	1 mm	-2 mm
Sep	37.2 °C	+1.0 °C	0 mm	-4 mm
Oct	37.9 °C	+1.1 °C	3 mm	-7 mm
Nov	37.3 °C	+1.1 °C	3 mm	-27 mm
Dec	34.8 °C	+0.2 °C	47 mm	-41 mm

The year's extremes

Hottest day

39.5 °C

14 Oct 2025

Coldest day

20.6 °C

18 Jul 2025

Wettest day

65.5 mm

17 Mar 2025

Windiest day

22.4 km/h

2 Sep 2025

Strongest gust

50.4 km/h

2 Sep 2025

Hottest feels-like

42.6 °C

20 Oct 2025

Coldest feels-like

21.4 °C

13 Jul 2025

Sunniest day

12.0 h

18 Nov 2025

What was the weather like that day?

Your birthday, a wedding, a memorable trip: discover the actual weather for any date since 1940.

Date

Frequently asked questions

What is the climate of União?

União has a tropical savanna climate (Köppen Aw). Over 1940-2025, the average annual temperature is 28.0 °C and it receives 1,509 mm of precipitation per year.

What is the hottest day ever recorded in União?

The hottest day measured in União between 1940 and 2025 was 20 November 2005, reaching 41.3 °C.

What is the coldest day in União?

The coldest day measured in União between 1940 and 2025 was 26 July 2024, at 17.9 °C.

Does it snow in União?

Almost never: União sees virtually no snow, with about 0 frost days per year.

Has the climate of União warmed?

Yes: União warmed by +0.8 °C between 1940 and 2025, a statistically significant trend.

What is the wettest day in União?

The wettest day measured in União between 1940 and 2025 was 9 April 1977, with 242 mm of rain in 24 hours.

What was the windiest day in União?

The windiest day measured in União between 1940 and 2025 was 5 July 2017, with winds reaching 26.5 km/h.

What is the warmest month in União?

The warmest month in União is October (30.4 °C on average); the coldest is March (26.0 °C).

How much does it rain in União?

União receives on average 1,509 mm of precipitation per year, spread over about 137 rainy days.

Is it sunny in União?

União gets on average 10.8 hours of sunshine per day, roughly 3,942 hours per year over 1940-2025.

Are there tropical nights in União?

Yes: União has on average 364 tropical nights per year (temperature staying above 20 °C), over 1940-2025.

What was the most extreme apparent temperature in União?

In União, between 1940 and 2025, the highest apparent temperature reached 44.7 °C on 14 October 2018, and the lowest was 18.7 °C on 3 August 2001.

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