Altos weather in September

In September, Altos sees average daytime highs of 36°C and overnight lows near 25°C, with 4 mm of rain across 0.8 wet days and about 12 hours of daylight. It is the 2nd-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 73% of the time in September, and the air most often feels humid.

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 Altos's 1st-clearest and 3rd-windiest month. For the whole year in context, see Altos's year-round climate.

Daytime high
36°
2nd warmest
Overnight low
25°
10th coldest
Rainfall
4 mm
0.8 wet days
Daylight
12 hours
5:45 AM – 5:43 PM
Cloud cover
33%
1st clearest
Wind
9 km/h
3rd windiest
Solar energy
6.66 kWh/m²
Travel score
2.3
out of 10

Altos is human settlement in Brazil.

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

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 Altos reaches about 36°C in the afternoon and slips back to 25°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 38°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)
13625
23625
33625
43625
53625
63625
73625
83625
93625
103625
113625
123625
133625
143625
153625
163725
173725
183725
193725
203725
213725
223725
233725
243725
253725
263725
273725
283725
293725
303725

How September really feels in Altos

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.

Altos weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan32° / 23°25722.412.32.7
Feb32° / 23°29922.512.22.7
Mar31° / 23°37127122.6
Apr31° / 23°29723.611.92.9
May32° / 23°12912.711.83.8
Jun33° / 23°183.511.74.2
Jul34° / 24°91.511.74.0
Aug35° / 24°20.511.83.2
Sep36° / 25°40.8122.3
Oct37° / 25°172.212.11.9
Nov36° / 25°375.512.22.1
Dec35° / 25°9711.212.32.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 73% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 11%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18911
28911
38911
48911
59010
68911
78911
88911
98911
108911
118911
128911
138911
148911
158911
168911
179010
189010
199010
208911
218911
229010
239010
249010
259010
268911
278911
288911
298911
308911

Chance of precipitation in September

Any precipitation

Altos gets around 4 mm of rain over 0.8 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 3% and peaks near 4% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
12
22
32
42
52
62
72
82
92
102
112
122
132
142
152
162
173
183
193
203
213
223
233
244
254
264
274
284
294
304

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 48% of days. Sticky, muggy-or-worse air turns up on roughly 39% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11453321
21453321
31453312
41453312
51454302
61554292
71554292
81554292
91653292
101653292
111653292
121652302
131552312
141552312
151550332
161549342
171448352
181447372
191346382
201245403
211244413
221144423
231043433
241042444
25942454
26941464
27841474
28841474
29740485
30740485

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
110calm
210calm
310calm
410calm
510calm
610calm
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
179calm
189calm
199calm
209calm
219calm
229calm
239calm
249calm
259calm
269calm
279calm
289calm
299calm
309calm

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 5:52 AM to 5:38 AM, and sunset from 5:47 PM to 5:40 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.95:525:47
211.95:525:46
311.95:525:46
411.95:515:46
511.95:515:46
611.95:505:46
711.95:505:45
811.95:495:45
911.95:495:45
1011.95:485:45
1111.95:485:44
1212.05:475:44
1312.05:475:44
1412.05:465:44
1512.05:455:44
1612.05:455:43
1712.05:445:43
1812.05:445:43
1912.05:435:43
2012.05:435:42
2112.05:425:42
2212.05:425:42
2312.05:415:42
2412.05:415:42
2512.05:405:41
2612.05:405:41
2712.05:395:41
2812.05:395:41
2912.05:385:41
3012.05:385:40

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.66 kWh/m².

For context, solar energy here swings from a low near 4.84 kWh/m² to a high of 6.72 kWh/m² in October across the year — September's 6.66 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.4Intense
26.5Intense
36.5Intense
46.5Intense
56.5Intense
66.5Intense
76.5Intense
86.6Intense
96.6Intense
106.6Intense
116.6Intense
126.6Intense
136.6Intense
146.7Intense
156.7Intense
166.7Intense
176.7Intense
186.7Intense
196.7Intense
206.7Intense
216.7Intense
226.7Intense
236.7Intense
246.7Intense
256.7Intense
266.8Intense
276.8Intense
286.8Intense
296.8Intense
306.8Intense
Planning a trip in September

Hazard calendar for Altos

In seasonPeak

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

Altos'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 Altos?

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

2.3
Sightseeing
10th-best month of the year
5.8
Beach & pool
5th-best month of the year

September is a weaker month for outdoor sightseeing in Altos.

What to pack for Altos in September

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

In September, Altos sees daytime highs around 36°C and nights near 25°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Altos 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 Altos peaks around March 14 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near August 10 at about 10 (very high).

The index reaches 3 or more — the level where the WHO recommends sun protection — every month of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highExtremeMar 14UV 15Aug 10UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar15Extreme
Apr13Extreme
May11Extreme
Jun10Very high
Jul10Very high
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov12Extreme
Dec11Extreme

Air quality in Altos in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Altos is worst in October — around 35 µg/m³ PM2.5 (moderate), about 4.2× the cleanest month (June, 8 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateOct 1633 µg/m³Jun 199 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb16Moderate
Mar15Moderate
Apr14Moderate
May12Good
Jun8Good
Jul10Good
Aug16Moderate
Sep25Moderate
Oct35Moderate
Nov23Moderate
Dec17Moderate
Location & terrain

Where is Altos?

Altos sits at 5.0°S, 42.5°W, 192 m above sea level, in Brazil. The nearest listed city is José de Freitas, 34 km away.

Topography around Altos

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

Within 3 km, the terrain around Altos has only modest variations in elevation — a maximum elevation change of 103 m around an average of 184 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 175 m; within 80 km, significant variations in elevation — a maximum elevation change of 375 m.

The land around Altos is covered by trees (30%), shrubs (26%) and grassland (23%) within 3 km, trees (58%), shrubs (21%) and grassland (20%) within 16 km, and trees (42%), shrubs (32%) and grassland (23%) within 80 km.

3 km
103 m
16 km
175 m
80 km
375 m
treesshrubsgrasslandcroplandartificial surfaces
September weather nearby: José de Freitas 34 km · Teresina 38 km · Campo Maior 40 km · Timon 42 km · Demerval Lobão 43 km · União 67 km · Barras 90 km · Água Branca 97 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 Altos (-5.0381°, -42.46°, elevation 192 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. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).