Rio Claro weather in September

In September, Rio Claro sees average daytime highs of 25°C and overnight lows near 16°C, with 78 mm of rain across 12.1 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 25°C through the month. The sky is clear or mostly clear about 33% 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 Rio Claro's 6th-clearest and 1st-windiest month. For the whole year in context, see Rio Claro's year-round climate.

Daytime high
25°
8th warmest
Overnight low
16°
5th coldest
Rainfall
78 mm
12.1 wet days
Daylight
11 h 54 min
6:55 AM – 6:47 PM
Cloud cover
61%
6th clearest
Wind
6 km/h
1st windiest
Solar energy
4.59 kWh/m²
Travel score
6.4
out of 10

Rio Claro is Place in Brasil.

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 25°C through the month.

A typical September day in Rio Claro reaches about 25°C in the afternoon and slips back to 16°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 31°C. Set against its neighbours, September runs about 1°C warmer than August and about 1°C cooler than October.

10°15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12515
22516
32516
42516
52516
62516
72516
82516
92516
102516
112516
122516
132516
142516
152516
162516
172516
182516
192516
202516
212517
222517
232517
242517
252517
262517
272517
282517
292517
302517

Rio Claro 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
Jan29° / 21°2952413.23.8
Feb29° / 21°2042012.83.9
Mar28° / 20°20122.812.24.4
Apr26° / 19°10214.111.55.9
May24° / 16°6310.710.96.8
Jun24° / 15°356.710.67.6
Jul23° / 14°40710.77.6
Aug24° / 15°367.311.27.6
Sep25° / 16°7812.111.96.4
Oct26° / 18°11516.112.55.5
Nov26° / 19°18820.413.14.8
Dec28° / 20°23723.113.44.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 33% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 11% of September, with mostly cloudy or overcast conditions the remaining 56%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15842
25842
35743
45644
55545
65446
75347
85248
95050
104951
114753
124753
134654
144555
154456
164258
174159
184060
193961
203862
213763
223664
233565
243466
253466
263268
273268
283169
293070
303169

Chance of precipitation in September

Any precipitation

Rio Claro gets around 78 mm of rain over 12.1 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 40% and peaks near 48% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
130
231
332
432
533
634
735
836
936
1037
1138
1238
1339
1439
1539
1640
1741
1842
1942
2043
2144
2244
2345
2445
2546
2646
2747
2847
2948
3048

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 44% of days. Sticky, muggy-or-worse air turns up on roughly 11% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
11346392
21346402
31245402
41245412
51245413
61144413
71144413
81143424
91043425
101042425
11942436
12941437
13840448
14839448
15739459
167384510
177374511
187354612
197344613
207334614
217324615
226314616
236304618
246294619
256274720
266264721
276264722
286254623
296244624
306244625

Wind in September

Winds average 6 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 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

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 7:10 AM to 6:40 AM, and sunset from 6:42 PM to 6:51 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.57:106:42
211.67:096:43
311.67:086:43
411.67:076:43
511.67:066:44
611.67:056:44
711.77:046:44
811.77:036:45
911.77:026:45
1011.77:016:45
1111.87:006:45
1211.86:596:46
1311.86:586:46
1411.86:576:46
1511.86:566:47
1611.96:556:47
1711.96:546:47
1811.96:536:48
1911.96:526:48
2012.06:516:48
2112.06:506:49
2212.06:486:49
2312.06:476:49
2412.16:466:49
2512.16:456:50
2612.16:446:50
2712.16:436:50
2812.16:426:51
2912.26:416:51
3012.26:406:51

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.59 kWh/m².

For context, solar energy here swings from a low near 3.4 kWh/m² to a high of 5.71 kWh/m² in February across the year — September's 4.59 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.6Bright
24.6Bright
34.6Bright
44.6Bright
54.6Bright
64.6Bright
74.6Bright
84.6Bright
94.6Bright
104.6Bright
114.6Bright
124.6Bright
134.6Bright
144.6Bright
154.6Bright
164.6Bright
174.6Bright
184.6Bright
194.6Bright
204.6Bright
214.6Bright
224.6Bright
234.6Bright
244.6Bright
254.6Bright
264.6Bright
274.6Bright
284.6Bright
294.7Bright
304.7Bright
Planning a trip in September

Hazard calendar for Rio Claro

In seasonPeak

None of Rio Claro'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 Claro's rainy season runs November–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 Rio Claro?

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

6.4
Sightseeing
5th-best month of the year
5.9
Beach & pool
4th-best month of the year

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

What to pack for Rio Claro in September

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

In September, Rio Claro sees daytime highs around 25°C and nights near 16°C. Worth packing: light clothes, rain gear and sun protection. About 12 days see rain.

light clothesrain gearsun protection

Sea temperature near Rio Claro in September

The nearest coast averages about 22°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 51 km away) is warmest in February at about 27°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°28°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb27Warm
Mar27Warm
Apr26Warm
May24Warm
Jun23Refreshing
Jul22Refreshing
Aug21Refreshing
Sep22Refreshing
Oct23Refreshing
Nov23Refreshing
Dec25Warm

UV index in Rio Claro in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Rio Claro peaks around February 9 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 12 at about 5 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighVery highExtremeFeb 9UV 14Jul 12UV 5
UV index (midday)Level
Jan14Extreme
Feb14Extreme
Mar12Extreme
Apr9Very high
May7High
Jun6High
Jul5High
Aug8Very high
Sep7High
Oct11Extreme
Nov13Extreme
Dec14Extreme

Air quality in Rio Claro 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 Rio Claro is worst in September — around 33 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (December, 15 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateSep 1332 µg/m³Dec 2115 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb16Moderate
Mar17Moderate
Apr19Moderate
May24Moderate
Jun29Moderate
Jul31Moderate
Aug27Moderate
Sep33Moderate
Oct20Moderate
Nov17Moderate
Dec15Moderate
Location & terrain

Where is Rio Claro?

Rio Claro sits at 22.7°S, 44.1°W, 464 m above sea level, in Brazil. The nearest listed city is Barra Mansa, 20 km away.

Topography around Rio Claro

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

Within 3 km, the terrain around Rio Claro has large variations in elevation — a maximum elevation change of 814 m around an average of 583 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,265 m; within 80 km, extreme variations in elevation — a maximum elevation change of 2,761 m.

The land around Rio Claro is covered by trees (50%) and grassland (48%) within 3 km, grassland (56%) and trees (43%) within 16 km, and trees (43%), grassland (29%) and water (24%) within 80 km.

3 km
814 m
16 km
1,265 m
80 km
2,761 m
treesgrasslandartificial surfaceswater
September weather nearby: Barra Mansa 20 km · Volta Redonda 22 km · Piraí 27 km · Pinheiral 27 km · Mangaratiba 28 km · Angra dos Reis 37 km · Porto Real 37 km · Itaguaí 40 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 Claro (-22.7231°, -44.1356°, elevation 464 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).