Niterói weather in September

In September, Niterói sees average daytime highs of 26°C and overnight lows near 20°C, with 66 mm of rain across 10.2 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 26°C through the month. The sky is clear or mostly clear about 40% of the time in September, and the air most often feels muggy.

Daylight stretches from about 11 h 30 min at the start of September to 12 h 12 min by month's end. Set against the rest of the year, September is Niterói's 6th-clearest and 1st-windiest month. For the whole year in context, see Niterói's year-round climate.

Daytime high
26°
9th warmest
Overnight low
20°
4th coldest
Rainfall
66 mm
10.2 wet days
Daylight
11 h 54 min
6:51 AM – 6:43 PM
Cloud cover
53%
6th clearest
Wind
13 km/h
1st windiest
Solar energy
4.71 kWh/m²
Travel score
6.9
out of 10
Air quality
Good
PM2.5 9 µg/m³ · 2015

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 26°C through the month.

A typical September day in Niterói reaches about 26°C in the afternoon and slips back to 20°C overnight — a 6°C spread between the day's warmth and the night's chill. On most days the high lands between 22°C and 30°C. Set against its neighbours, September runs on par with August and on par with October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12520
22620
32620
42620
52620
62620
72620
82620
92620
102620
112620
122620
132620
142620
152620
162620
172620
182520
192520
202520
212520
222520
232520
242520
252520
262520
272520
282520
292520
302620

How September really feels in Niterói

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.

Niterói 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°14515.213.24.6
Feb30° / 25°9311.912.84.7
Mar29° / 24°12715.312.24.9
Apr28° / 23°7711.411.56.2
May26° / 21°7010.710.96.8
Jun25° / 20°416.710.67.6
Jul25° / 19°457.710.77.6
Aug25° / 19°367.211.27.6
Sep26° / 20°6610.211.96.9
Oct26° / 21°8010.612.56.4
Nov27° / 22°12214.813.15.7
Dec28° / 24°13315.113.45.1

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 40% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 13% of September, with mostly cloudy or overcast conditions the remaining 47%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16634
26535
36436
46436
56337
66238
76139
86040
95941
105842
115743
125644
135446
145347
155248
165248
175050
184951
194951
204852
214654
224654
234555
244555
254456
264555
274357
284357
294258
304357

Chance of precipitation in September

Any precipitation

Niterói gets around 66 mm of rain over 10.2 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 33% and peaks near 39% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
126
226
326
427
527
627
728
828
929
1029
1130
1230
1330
1431
1531
1632
1733
1834
1935
2036
2136
2237
2338
2438
2538
2639
2739
2839
2939
3038

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 46% of days. Sticky, muggy-or-worse air turns up on roughly 51% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
121143441
221143441
321143441
421143441
511143441
611043441
711044431
811044431
911044442
1011044442
111944442
121943452
131943453
141842463
151841473
161841473
171840484
181839494
191838494
201837495
211836495
222835496
232834497
242833498
252833498
262832499
2728324810
2828314811
2928314711
3028314712

Wind in September

Winds average 13 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 13 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
113light breeze
213light breeze
313light breeze
413light breeze
513light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1314light breeze
1414light breeze
1514light breeze
1614light breeze
1714light breeze
1814light breeze
1914light breeze
2014light 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 30 min at the start of September to 12 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 42 minutes over September. Sunrise moves from 7:06 AM to 6:36 AM, and sunset from 6:38 PM to 6:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.57:066:38
211.67:056:39
311.67:046:39
411.67:036:39
511.67:026:39
611.67:016:40
711.77:006:40
811.76:596:40
911.76:586:41
1011.76:576:41
1111.86:566:41
1211.86:556:42
1311.86:546:42
1411.86:536:42
1511.86:526:43
1611.96:516:43
1711.96:506:43
1811.96:496:43
1911.96:476:44
2012.06:466:44
2112.06:456:44
2212.06:446:45
2312.06:436:45
2412.16:426:45
2512.16:416:46
2612.16:406:46
2712.16:396:46
2812.16:386:47
2912.26:376:47
3012.26:366:47

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.71 kWh/m².

For context, solar energy here swings from a low near 3.38 kWh/m² to a high of 6.15 kWh/m² in February across the year — September's 4.71 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.7Bright
24.7Bright
34.7Bright
44.7Bright
54.7Bright
64.7Bright
74.7Bright
84.7Bright
94.7Bright
104.7Bright
114.7Bright
124.7Bright
134.7Bright
144.7Bright
154.8Bright
164.8Bright
174.8Bright
184.8Bright
194.8Bright
204.8Bright
214.8Bright
224.8Bright
234.8Bright
244.8Bright
254.8Bright
264.8Bright
274.8Bright
284.8Bright
294.8Bright
304.9Bright
Planning a trip in September

Is September a good time to visit Niterói?

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

6.9
Sightseeing
4th-best month of the year
6.4
Beach & pool
6th-best month of the year

September is a reasonable time to visit Niterói for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Niterói in September

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

In September, Niterói sees daytime highs around 26°C and nights near 20°C. Worth packing: light clothes, rain gear and sun protection. About 10 days see rain.

light clothesrain gearsun protection

Sea temperature near Niterói in September

The nearest coast averages about 21°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 27 km away) is warmest in March at about 25°C and coldest in August near 21°C.

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

20°22°24°26°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan25Warm
Feb25Warm
Mar25Warm
Apr25Warm
May24Refreshing
Jun23Refreshing
Jul22Refreshing
Aug21Refreshing
Sep21Refreshing
Oct22Refreshing
Nov23Refreshing
Dec24Warm

UV index in Niterói in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Niterói peaks around January 13 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 13 at about 5 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighExtremeJan 13UV 14Jul 13UV 5
UV index (midday)Level
Jan14Extreme
Feb13Extreme
Mar12Extreme
Apr9Very high
May6High
Jun6High
Jul5Moderate
Aug8Very high
Sep6High
Oct11Extreme
Nov13Extreme
Dec14Extreme
Location & terrain

Where is Niterói?

Niterói sits at 22.9°S, 43.1°W, 44 m above sea level, in Brazil. The nearest listed city is Rio de Janeiro, 8.0 km away.

Topography around Niterói

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

Within 3 km, the terrain around Niterói has only modest variations in elevation — a maximum elevation change of 207 m around an average of 36 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 769 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,252 m.

The land around Niterói is covered by artificial surfaces (55%) and trees (26%) within 3 km, water (45%), trees (25%) and artificial surfaces (25%) within 16 km, and trees (38%) and water (34%) within 80 km.

3 km
207 m
16 km
769 m
80 km
2,252 m
treesgrasslandartificial surfaceswaterwetlandmangroves
September weather nearby: Rio de Janeiro 8.0 km · Catete 9.0 km · Santa Teresa 9.0 km · Estácio 11 km · Copacabana 13 km · Ipanema 15 km · Leblon 17 km · Vidigal 19 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 Niterói (-22.8833°, -43.1036°, elevation 44 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).