Viana weather in September

In September, Viana sees average daytime highs of 34°C and overnight lows near 25°C, with 9 mm of rain across 2 wet days and about 12 hours of daylight. It is the 2nd-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 34°C through the month. The sky is clear or mostly clear about 65% of the time in September, and the air most often feels oppressive.

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 Viana's 2nd-clearest and 2nd-windiest month. For the whole year in context, see Viana's year-round climate.

Daytime high
34°
2nd warmest
Overnight low
25°
9th coldest
Rainfall
9 mm
2 wet days
Daylight
12 hours
5:55 AM – 5:54 PM
Cloud cover
38%
2nd clearest
Wind
12 km/h
2nd windiest
Solar energy
6.12 kWh/m²
Travel score
3.7
out of 10

Viana 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 34°C through the month.

A typical September day in Viana reaches about 34°C in the afternoon and slips back to 25°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 33°C and 36°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)
13425
23425
33425
43425
53425
63425
73425
83425
93425
103425
113425
123425
133425
143425
153425
163425
173425
183425
193425
203425
213425
223425
233425
243425
253425
263425
273425
283425
293425
303425

How September really feels in Viana

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
14 feel dangerously hot (≥ 39°C)
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.

Viana weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan32° / 25°20524.412.22.7
Feb31° / 24°27925.512.12.5
Mar31° / 24°35529.5122.4
Apr31° / 24°36728.211.92.4
May31° / 25°20223.411.93.0
Jun31° / 24°7914.511.83.9
Jul32° / 24°5010.111.84.4
Aug33° / 24°153.911.94.2
Sep34° / 25°92123.7
Oct34° / 25°183.512.13.3
Nov34° / 25°396.612.13.3
Dec33° / 25°911412.23.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 65% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 24% of September, with mostly cloudy or overcast conditions the remaining 12%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1919
2919
3919
49010
59010
69010
79010
89010
99010
109010
119010
128911
138911
148911
158911
168911
178911
188812
198812
208812
218812
228713
238713
248713
258713
268614
278614
288614
298515
308416

Chance of precipitation in September

Any precipitation

Viana gets around 9 mm of rain over 2 wet days in September, the driest month. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 7% and peaks near 8% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
18
28
38
47
57
67
76
86
96
106
116
126
136
146
157
167
177
187
197
207
218
228
238
248
258
268
278
288
298
308

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 92% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Muggy (%)Oppressive (%)Miserable (%)
13898
24897
34897
44906
54915
65914
75914
85923
95923
105923
115932
125932
135932
145932
155932
165932
175923
185923
195923
205923
215923
225923
234933
244942
254942
264942
274942
284942
294942
304942

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 11 km/h on the calmest days to 13 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
111calm
211calm
311calm
412calm
512calm
612calm
712calm
812calm
912calm
1012calm
1112calm
1212light breeze
1312light breeze
1412light breeze
1512light breeze
1612light breeze
1712light breeze
1812light breeze
1913light breeze
2013light breeze
2113light breeze
2213light breeze
2313light breeze
2413light breeze
2513light breeze
2613light breeze
2713light breeze
2813light breeze
2913light breeze
3013light 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 6:02 AM to 5:49 AM, and sunset from 5:58 PM to 5:50 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.96:025:58
211.96:015:58
311.96:015:57
411.96:005:57
511.96:005:57
612.05:595:57
712.05:595:56
812.05:595:56
912.05:585:56
1012.05:585:55
1112.05:575:55
1212.05:575:55
1312.05:565:55
1412.05:565:54
1512.05:555:54
1612.05:555:54
1712.05:545:54
1812.05:545:53
1912.05:535:53
2012.05:535:53
2112.05:535:52
2212.05:525:52
2312.05:525:52
2412.05:515:52
2512.05:515:51
2612.05:505:51
2712.05:505:51
2812.05:495:51
2912.05:495:50
3012.05:495:50

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.12 kWh/m².

For context, solar energy here swings from a low near 4.22 kWh/m² to a high of 6.22 kWh/m² in October across the year — September's 6.12 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.9Bright
26.0Bright
36.0Bright
46.0Bright
56.0Intense
66.0Intense
76.0Intense
86.0Intense
96.1Intense
106.1Intense
116.1Intense
126.1Intense
136.1Intense
146.1Intense
156.1Intense
166.1Intense
176.1Intense
186.2Intense
196.2Intense
206.2Intense
216.2Intense
226.2Intense
236.2Intense
246.2Intense
256.2Intense
266.2Intense
276.2Intense
286.2Intense
296.2Intense
306.2Intense
Planning a trip in September

Hazard calendar for Viana

In seasonPeak

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

Viana's monsoon runs January–May, 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 Viana?

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

3.7
Sightseeing
4th-best month of the year
7.3
Beach & pool
2nd-best month of the year

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

What to pack for Viana in September

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

In September, Viana sees daytime highs around 34°C and nights near 25°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Viana 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 Viana peaks around March 17 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 15 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 17UV 15Jul 15UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar15Extreme
Apr14Extreme
May11Extreme
Jun10Extreme
Jul10Very high
Aug10Extreme
Sep12Extreme
Oct12Extreme
Nov10Extreme
Dec11Extreme

Air quality in Viana 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 Viana is worst in November — around 18 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (June, 9 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateNov 1918 µg/m³Jun 199 µg/m³
PM2.5 (µg/m³)Level
Jan15Moderate
Feb17Moderate
Mar16Moderate
Apr14Moderate
May10Good
Jun9Good
Jul9Good
Aug10Good
Sep9Good
Oct13Moderate
Nov18Moderate
Dec16Moderate
Location & terrain

Where is Viana?

Viana sits at 3.2°S, 45.0°W, 13 m above sea level, in Brazil. The nearest listed city is Cajari, 11 km away.

Topography around Viana

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

Within 3 km, the terrain around Viana has only modest variations in elevation — a maximum elevation change of 30 m around an average of 6 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 55 m; within 80 km, only modest variations in elevation — a maximum elevation change of 169 m.

The land around Viana is covered by water (38%), wetland (25%) and grassland (20%) within 3 km, grassland (47%), wetland (22%) and trees (21%) within 16 km, and grassland (41%) and trees (38%) within 80 km.

3 km
30 m
16 km
55 m
80 km
169 m
treesgrasslandcroplandartificial surfaceswaterwetlandmangroves
September weather nearby: Cajari 11 km · Matinha 14 km · Penalva 21 km · Vitória do Mearim 31 km · Arari 36 km · São João Batista 37 km · São Vicente Ferrer 39 km · Monção 41 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 Viana (-3.2203°, -45.0036°, elevation 13 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).