Rio Formoso weather in September

In September, Rio Formoso sees average daytime highs of 28°C and overnight lows near 21°C, with 54 mm of rain across 17.5 wet days and about 11.9 hours of daylight. It is the 9th-warmest and 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near 28°C through the month. The sky is clear or mostly clear about 24% of the time in September, and the air most often feels muggy.

Daylight stretches from about 11 h 48 min at the start of September to 12 h 06 min by month's end. Set against the rest of the year, September is Rio Formoso's 1st-clearest and 4th-windiest month. For the whole year in context, see Rio Formoso's year-round climate.

Daytime high
28°
9th warmest
Overnight low
21°
3rd coldest
Rainfall
54 mm
17.5 wet days
Daylight
12 hours
5:16 AM – 5:14 PM
Cloud cover
51%
1st clearest
Wind
10 km/h
4th windiest
Solar energy
5.19 kWh/m²
Travel score
5.3
out of 10

Rio Formoso is 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 28°C through the month.

A typical September day in Rio Formoso reaches about 28°C in the afternoon and slips back to 21°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 26°C and 29°C. Set against its neighbours, September runs about 1°C warmer than August and about 1°C cooler than October.

20°23°25°28°30°151015202530
Avg high (°C)Avg low (°C)
12721
22721
32721
42721
52721
62721
72721
82721
92721
102721
112721
122721
132821
142821
152821
162821
172821
182821
192822
202822
212822
222822
232822
242822
252822
262822
272822
282822
292822
302822

How September really feels in Rio Formoso

Once humidity and wind are folded in, September averages 0 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
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Rio Formoso weather by month

How September compares with the rest of the year at a glance. September is the 9th-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 24°5617.312.44.1
Feb31° / 24°6116.912.33.8
Mar31° / 24°8019.512.13.8
Apr30° / 24°942111.83.8
May29° / 23°12324.111.63.9
Jun27° / 22°14124.711.54.3
Jul27° / 21°12324.811.54.5
Aug27° / 21°7822.211.74.8
Sep28° / 21°5417.511.95.3
Oct29° / 22°3814.712.25.1
Nov30° / 23°3011.512.45.0
Dec30° / 23°3212.512.54.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 24% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 49% of September, with mostly cloudy or overcast conditions the remaining 27%. Skies tend to open up as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17030
27030
37030
47030
57030
66931
76931
86931
97030
107030
117030
127129
137129
147228
157327
167327
177426
187525
197525
207525
217723
227723
237822
247822
257822
267822
277822
287822
297822
307822

Chance of precipitation in September

Any precipitation

Rio Formoso gets around 54 mm of rain over 17.5 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 58% and peaks near 68% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
168
268
367
467
567
667
767
866
966
1066
1165
1264
1363
1462
1561
1660
1758
1857
1956
2054
2153
2251
2350
2449
2548
2647
2746
2846
2946
3046

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 68% of days. Sticky, muggy-or-worse air turns up on roughly 99% of them.

0%25%50%75%100%151015202530
Humid (%)Muggy (%)Oppressive (%)
127028
227028
326929
426929
526929
626929
726929
826929
926929
1026929
1126929
1226830
1326830
1416930
1516930
1616930
1716930
1816930
1916831
2016831
2116831
2216732
2316732
2416633
2516534
2616435
2716435
2816336
2916237
3016138

Wind in September

Winds average 10 km/h in September.

Across September, daily wind ranges from about 10 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
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
2510calm
2610calm
2710calm
2810calm
2910calm
3010calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 48 min at the start of September to 12 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 18 minutes over September. Sunrise moves from 5:25 AM to 5:08 AM, and sunset from 5:15 PM to 5:12 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.85:255:15
211.85:255:15
311.85:245:15
411.95:245:15
511.95:235:15
611.95:225:15
711.95:225:15
811.95:215:15
911.95:215:14
1011.95:205:14
1111.95:195:14
1211.95:195:14
1311.95:185:14
1411.95:185:14
1511.95:175:14
1612.05:165:14
1712.05:165:13
1812.05:155:13
1912.05:155:13
2012.05:145:13
2112.05:135:13
2212.05:135:13
2312.05:125:13
2412.05:115:13
2512.05:115:12
2612.05:105:12
2712.05:105:12
2812.15:095:12
2912.15:095:12
3012.15:085:12

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.19 kWh/m².

For context, solar energy here swings from a low near 3.87 kWh/m² to a high of 5.85 kWh/m² in November across the year — September's 5.19 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.9Bright
34.9Bright
44.9Bright
54.9Bright
65.0Bright
75.0Bright
85.0Bright
95.0Bright
105.0Bright
115.0Bright
125.1Bright
135.1Bright
145.1Bright
155.2Bright
165.2Bright
175.2Bright
185.2Bright
195.3Bright
205.3Bright
215.3Bright
225.4Bright
235.4Bright
245.4Bright
255.4Bright
265.5Bright
275.5Bright
285.5Bright
295.5Bright
305.5Bright
Planning a trip in September

Hazard calendar for Rio Formoso

In seasonPeak

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

Rio Formoso's rainy season runs March–August, when most of the year's rain falls.

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

Is September a good time to visit Rio Formoso?

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

5.3
Sightseeing
1st-best month of the year
5.7
Beach & pool
5th-best month of the year

September is a reasonable time to visit Rio Formoso for sightseeing.

What to pack for Rio Formoso in September

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

In September, Rio Formoso sees daytime highs around 28°C and nights near 21°C. Pack light clothes and rain gear. Worth having: sun protection. About 18 days see rain.

light clothesrain gearsun protection

Sea temperature near Rio Formoso in September

The nearest coast averages about 26°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 23 km away) is warmest in April at about 29°C and coldest in August near 26°C.

The water stays above 20°C all year — warm enough for a swim any month.

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Warm
Feb28Tropical
Mar29Tropical
Apr29Tropical
May28Tropical
Jun27Warm
Jul26Warm
Aug26Warm
Sep26Warm
Oct27Warm
Nov27Warm
Dec27Warm

UV index in Rio Formoso 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 Rio Formoso peaks around March 14 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 23 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 15Jun 23UV 10
UV index (midday)Level
Jan14Extreme
Feb14Extreme
Mar15Extreme
Apr13Extreme
May11Extreme
Jun10Very high
Jul10Very high
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov12Extreme
Dec12Extreme
Location & terrain

Where is Rio Formoso?

Rio Formoso sits at 8.7°S, 35.2°W, 87 m above sea level, in Brazil. The nearest listed city is Sirinhaém, 10 km away.

Topography around Rio Formoso

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

Within 3 km, the terrain around Rio Formoso has only modest variations in elevation — a maximum elevation change of 138 m around an average of 70 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 179 m; within 80 km, large variations in elevation — a maximum elevation change of 859 m.

The land around Rio Formoso is covered by trees (55%) and grassland (35%) within 3 km, trees (36%) and grassland (32%) within 16 km, and grassland (43%) and water (32%) within 80 km.

3 km
138 m
16 km
179 m
80 km
859 m
treesgrasslandcroplandartificial surfaceswatermangroves
September weather nearby: Sirinhaém 10 km · Tamandaré 12 km · Barreiros 17 km · São José da Coroa Grande 26 km · Gameleira 26 km · Ribeirão 29 km · Porto de Galinhas 32 km · Escada 35 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 Rio Formoso (-8.6688°, -35.1628°, elevation 87 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. 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).