São João de Meriti weather in September

In September, São João de Meriti sees average daytime highs of 27°C and overnight lows near 18°C, with 87 mm of rain across 11.1 wet days and about 11.9 hours of daylight. It is the 8th-warmest and 8th-wettest month of the year here.

Day-to-day highs hold fairly steady near 27°C through the month. The sky is clear or mostly clear about 35% of the time in September, and the air most often feels humid.

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 São João de Meriti's 6th-clearest and 1st-windiest month. For the whole year in context, see São João de Meriti's year-round climate.

Daytime high
27°
8th warmest
Overnight low
18°
4th coldest
Rainfall
87 mm
11.1 wet days
Daylight
11 h 54 min
6:52 AM – 6:44 PM
Cloud cover
57%
6th clearest
Wind
7 km/h
1st windiest
Solar energy
4.52 kWh/m²
Travel score
6.3
out of 10

São João de Meriti is human settlement in Brazil.

Air quality
Moderate
PM2.5 12 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 27°C through the month.

A typical September day in São João de Meriti reaches about 27°C in the afternoon and slips back to 18°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 21°C and 33°C. Set against its neighbours, September runs on par with August and about 1°C cooler than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12717
22717
32718
42718
52718
62718
72718
82718
92718
102718
112718
122718
132718
142718
152718
162718
172718
182718
192718
202718
212718
222718
232719
242719
252719
262719
272719
282719
292719
302719

How September really feels in São João de Meriti

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.

São João de Meriti weather by month

How September compares with the rest of the year at a glance. September is the 8th-warmest and 8th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 23°26621.313.23.2
Feb32° / 23°19717.812.83.3
Mar30° / 22°21621.112.23.7
Apr29° / 21°10613.511.55.2
May26° / 18°7411.110.96.6
Jun26° / 17°477.110.67.3
Jul26° / 16°477.210.77.4
Aug26° / 17°447.511.27.2
Sep27° / 18°8711.111.96.3
Oct28° / 20°12014.412.55.3
Nov28° / 21°2131913.14.4
Dec30° / 22°23721.213.43.6

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 35% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 12% of September, with mostly cloudy or overcast conditions the remaining 53%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16238
26238
36040
46040
55941
65842
75743
85644
95545
105347
115248
125050
134951
144852
154753
164654
174456
184258
194258
204159
214060
223961
233862
243862
253763
263763
273565
283565
293565
303466

Chance of precipitation in September

Any precipitation

São João de Meriti gets around 87 mm of rain over 11.1 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 37% and peaks near 46% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
128
228
329
429
530
630
731
831
932
1032
1133
1233
1334
1435
1535
1636
1737
1838
1939
2040
2140
2241
2342
2443
2544
2644
2745
2845
2945
3046

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 46% of days. Sticky, muggy-or-worse air turns up on roughly 38% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
122153240
222153240
322053250
422053250
522052260
621953260
721952270
821852280
921851290
1011751310
1111651320
1211650331
1311549351
1411448361
1511448371
1611347381
1711246391
1811245401
1921144412
2021144422
2121043422
2221042433
2331041434
2431040434
253940435
263939436
273939437
283938437
293938438
303937438

Wind in September

Winds average 7 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
27calm
37calm
47calm
57calm
67calm
77calm
87calm
97calm
107calm
117calm
127calm
137calm
147calm
157calm
167calm
177calm
187calm
197calm
207calm
217calm
227calm
237calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

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 7:07 AM to 6:37 AM, and sunset from 6:39 PM to 6:48 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.57:076:39
211.67:066:40
311.67:056:40
411.67:046:40
511.67:036:41
611.67:026:41
711.77:016:41
811.77:006:41
911.76:596:42
1011.76:586:42
1111.86:576:42
1211.86:566:43
1311.86:556:43
1411.86:546:43
1511.86:536:44
1611.96:526:44
1711.96:516:44
1811.96:506:45
1911.96:496:45
2012.06:486:45
2112.06:466:45
2212.06:456:46
2312.06:446:46
2412.16:436:46
2512.16:426:47
2612.16:416:47
2712.16:406:47
2812.16:396:48
2912.26:386:48
3012.26:376:48

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.52 kWh/m².

For context, solar energy here swings from a low near 3.33 kWh/m² to a high of 5.93 kWh/m² in February across the year — September's 4.52 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.5Bright
24.5Bright
34.5Bright
44.5Bright
54.6Bright
64.6Bright
74.6Bright
84.6Bright
94.6Bright
104.6Bright
114.6Bright
124.6Bright
134.6Bright
144.5Bright
154.5Bright
164.5Bright
174.5Bright
184.5Bright
194.5Bright
204.5Bright
214.5Bright
224.5Bright
234.5Bright
244.5Bright
254.5Bright
264.5Bright
274.5Bright
284.6Bright
294.6Bright
304.6Bright
Planning a trip in September

Hazard calendar for São João de Meriti

In seasonPeak

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

São João de Meriti's rainy season runs October–March, 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 São João de Meriti?

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

6.3
Sightseeing
5th-best month of the year
6.5
Beach & pool
4th-best month of the year

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

What to pack for São João de Meriti in September

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

In September, São João de Meriti sees daytime highs around 27°C and nights near 18°C. Pack light clothes. Worth having: rain gear and sun protection. About 11 days see rain.

light clothesrain gearsun protection

Sea temperature near São João de Meriti 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 36 km away) is warmest in March at about 26°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
Mar26Warm
Apr25Warm
May24Refreshing
Jun23Refreshing
Jul22Refreshing
Aug21Refreshing
Sep21Refreshing
Oct22Refreshing
Nov22Refreshing
Dec24Warm

UV index in São João de Meriti 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 São João de Meriti 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

Air quality in São João de Meriti 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 São João de Meriti is worst in July — around 17 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (December, 8 µg/m³).

Seasonal pattern from CAMS reanalysis, scaled to São João de Meriti's WHO annual average of 12 µg/m³.

01020JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodJul 1217 µg/m³Dec 238 µg/m³
PM2.5 (µg/m³)Level
Jan8Good
Feb8Good
Mar9Good
Apr11Good
May14Moderate
Jun16Moderate
Jul17Moderate
Aug14Moderate
Sep17Moderate
Oct11Good
Nov9Good
Dec8Good
Location & terrain

Where is São João de Meriti?

São João de Meriti sits at 22.8°S, 43.4°W, 14 m above sea level, in Brazil. The nearest listed city is Nilópolis, 4.0 km away.

Topography around São João de Meriti

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of São João de Meriti.

Within 3 km, the terrain around São João de Meriti has only modest variations in elevation — a maximum elevation change of 154 m around an average of 27 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 956 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,224 m.

The land around São João de Meriti is covered by artificial surfaces (88%) within 3 km, artificial surfaces (52%) and trees (28%) within 16 km, and trees (37%), water (31%) and grassland (24%) within 80 km.

3 km
154 m
16 km
956 m
80 km
2,224 m
treesgrasslandartificial surfacesbare terrainwaterwetlandmangroves
September weather nearby: Nilópolis 4.0 km · Belford Roxo 5.0 km · Duque de Caxias 7.0 km · Nova Iguaçu 9.0 km · Queimados 21 km · Estácio 21 km · Barra da Tijuca 22 km · Rio de Janeiro 23 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 São João de Meriti (-22.8039°, -43.3722°, elevation 14 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. 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).