Castelo do Piauí weather in September

In September, Castelo do Piauí sees average daytime highs of 36°C and overnight lows near 24°C, with 1 mm of rain across 0.3 wet days and about 12 hours of daylight. It is the 3rd-warmest and 11th-wettest month of the year here.

Day-to-day highs hold fairly steady near 36°C through the month. The sky is clear or mostly clear about 78% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 11 h 54 min at the start of September to 12 hours by month's end. Set against the rest of the year, September is Castelo do Piauí's 1st-clearest and 1st-windiest month. For the whole year in context, see Castelo do Piauí's year-round climate.

Daytime high
36°
3rd warmest
Overnight low
24°
9th coldest
Rainfall
1 mm
0.3 wet days
Daylight
12 hours
5:41 AM – 5:40 PM
Cloud cover
27%
1st clearest
Wind
15 km/h
1st windiest
Solar energy
6.89 kWh/m²
Travel score
2.5
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 36°C through the month.

A typical September day in Castelo do Piauí reaches about 36°C in the afternoon and slips back to 24°C overnight — a 12°C spread between the day's warmth and the night's chill. On most days the high lands between 35°C and 37°C. Set against its neighbours, September runs about 1°C warmer than August and on par with October.

20°25°30°35°40°151015202530
Avg high (°C)Avg low (°C)
13624
23624
33624
43624
53624
63624
73624
83624
93624
103624
113624
123624
133624
143624
153624
163624
173624
183624
193624
203624
213624
223724
233724
243724
253724
263724
273725
283725
293725
303725

How September really feels in Castelo do Piauí

Once humidity and wind are folded in, September averages 30 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
30
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

The story in September is heat — humidity pushes the afternoon "feels like" well above the raw temperature.

Castelo do Piauí weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan33° / 24°15616.512.32.8
Feb32° / 23°17917.112.22.9
Mar32° / 23°25721.8122.9
Apr32° / 23°18418.311.93.3
May32° / 23°768.811.83.9
Jun33° / 23°11211.74.2
Jul34° / 23°61.111.74.0
Aug35° / 24°10.111.83.3
Sep36° / 24°10.3122.5
Oct37° / 25°140.812.12.0
Nov37° / 25°142.612.22.1
Dec36° / 25°416.712.32.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 78% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 14% of September, with mostly cloudy or overcast conditions the remaining 7%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1937
2937
3937
4937
5937
6937
7937
8937
9937
10937
11937
12937
13937
14937
15937
16937
17937
18937
19937
20937
21937
22937
23937
24928
25928
26928
27928
28928
29919
309010

Chance of precipitation in September

Any precipitation

Castelo do Piauí gets around 1 mm of rain over 0.3 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 1% and peaks near 1% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
11
21
31
41
51
61
71
81
91
101
111
121
131
141
151
161
171
181
191
201
211
221
231
241
251
261
271
281
291
301

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels comfortable — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the comfortable band about 48% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
1353422
2354412
3354412
4353413
5353413
6452413
7452413
8452413
9452413
10452413
11451423
12352423
13351433
14350443
15349453
16348463
17247473
18246483
19246493
20245503
21244513
22244513
23143533
24143533
25143533
26142543
27142534
28142534
29141544
30141544

Wind in September

Winds average 15 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 15 km/h on the calmest days to 15 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
115light breeze
215light breeze
315light breeze
415light breeze
515light breeze
615light breeze
715light breeze
815light breeze
915light breeze
1015light breeze
1115light breeze
1215light breeze
1315light breeze
1415light breeze
1515light breeze
1615light breeze
1715light breeze
1815light breeze
1915light breeze
2015light breeze
2115light breeze
2215light breeze
2315light breeze
2415light breeze
2515light breeze
2615light breeze
2715light breeze
2815light breeze
2915light breeze
3015light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 54 min at the start of September to 12 hours by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 6 minutes over September. Sunrise moves from 5:49 AM to 5:34 AM, and sunset from 5:43 PM to 5:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.95:495:43
211.95:495:43
311.95:485:42
411.95:485:42
511.95:475:42
611.95:475:42
711.95:465:42
811.95:465:41
911.95:455:41
1011.95:455:41
1111.95:445:41
1212.05:435:41
1312.05:435:40
1412.05:425:40
1512.05:425:40
1612.05:415:40
1712.05:415:39
1812.05:405:39
1912.05:405:39
2012.05:395:39
2112.05:395:39
2212.05:385:38
2312.05:385:38
2412.05:375:38
2512.05:375:38
2612.05:365:38
2712.05:365:37
2812.05:355:37
2912.05:355:37
3012.05:345:37

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.89 kWh/m².

For context, solar energy here swings from a low near 4.99 kWh/m² to a high of 6.94 kWh/m² in October across the year — September's 6.89 kWh/m² sits near the top of that range.

02468151015202530
Solar energy (kWh/m²)Level
16.7Intense
26.7Intense
36.7Intense
46.7Intense
56.7Intense
66.8Intense
76.8Intense
86.8Intense
96.8Intense
106.8Intense
116.8Intense
126.8Intense
136.9Intense
146.9Intense
156.9Intense
166.9Intense
176.9Intense
186.9Intense
196.9Intense
207.0Intense
217.0Intense
227.0Intense
237.0Intense
247.0Intense
257.0Intense
267.0Intense
277.0Intense
287.0Intense
297.0Intense
307.0Intense
Planning a trip in September

Hazard calendar for Castelo do Piauí

In seasonPeak

None of Castelo do Piauí's seasonal hazards are active in September. The full-year calendar below shows when the rainy season, cyclone risk and dust haze do peak.

Castelo do Piauí's monsoon runs January–April, when most of the year's rain falls.

Monsoon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Castelo do Piauí?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

2.5
Sightseeing
9th-best month of the year
6.1
Beach & pool
5th-best month of the year

September is a weaker month for outdoor sightseeing in Castelo do Piauí. The water and warmth also suit a beach or pool day.

What to pack for Castelo do Piauí in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Castelo do Piauí sees daytime highs around 36°C and nights near 24°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Castelo do Piauí in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 12 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Castelo do Piauí peaks around March 15 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.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeExtremeMar 15UV 15Jul 24UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar15Extreme
Apr14Extreme
May11Extreme
Jun10Extreme
Jul10Very high
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov12Extreme
Dec11Extreme
Location & terrain

Where is Castelo do Piauí?

Castelo do Piauí sits at 5.3°S, 41.6°W, 241 m above sea level, in Brazil. The nearest listed city is São Miguel do Tapuio, 32 km away.

Topography around Castelo do Piauí

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Castelo do Piauí.

Within 3 km, the terrain around Castelo do Piauí has only modest variations in elevation — a maximum elevation change of 82 m around an average of 249 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 300 m; within 80 km, large variations in elevation — a maximum elevation change of 790 m.

The land around Castelo do Piauí is covered by shrubs (67%) within 3 km, shrubs (63%) and trees (31%) within 16 km, and shrubs (65%) and trees (27%) within 80 km.

3 km
82 m
16 km
300 m
80 km
790 m
treesshrubsgrasslandcroplandartificial surfaces
September weather nearby: São Miguel do Tapuio 32 km · Campo Maior 88 km · Novo Oriente 89 km · Crateús 99 km · Pedro II 100 km · Altos 105 km · Quiterianópolis 111 km · Piripiri 119 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
Roman Catholic 57%Evangelical 27%none 9%other 4%

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 Castelo do Piauí (-5.3222°, -41.5525°, elevation 241 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. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).