Ilha Grande weather in September

In September, Ilha Grande sees average daytime highs of 29°C and overnight lows near 26°C, with 1 mm of rain across 0.2 wet days and about 12 hours of daylight. It is the 3rd-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 29°C through the month. The sky is clear or mostly clear about 88% 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 Ilha Grande's 1st-clearest and 2nd-windiest month. For the whole year in context, see Ilha Grande's year-round climate.

Daytime high
29°
3rd warmest
Overnight low
26°
5th coldest
Rainfall
1 mm
0.2 wet days
Daylight
12 hours
5:42 AM – 5:41 PM
Cloud cover
19%
1st clearest
Wind
30 km/h
2nd windiest
Solar energy
6.97 kWh/m²
Travel score
7.2
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 29°C through the month.

A typical September day in Ilha Grande reaches about 29°C in the afternoon and slips back to 26°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 28°C and 30°C. Set against its neighbours, September runs on par with August and on par with October.

24°26°28°30°32°151015202530
Avg high (°C)Avg low (°C)
12926
22926
32926
42926
52926
62926
72926
82926
92926
102926
112926
122926
132926
142926
152926
162926
172926
182926
192926
202926
212926
222926
232926
242926
252926
262926
272926
282926
292926
302926

How September really feels in Ilha Grande

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
heat index over the day's high
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.

Ilha Grande weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 26°14621.312.14.3
Feb28° / 26°21123.712.13.9
Mar28° / 25°32328.3123.7
Apr28° / 26°34327.311.93.5
May29° / 26°17820.711.94.3
Jun29° / 26°5111.311.85.5
Jul29° / 26°224.311.96.5
Aug30° / 26°20.411.97.0
Sep29° / 26°10.2127.2
Oct29° / 26°60.812.17.1
Nov29° / 26°71.612.16.8
Dec29° / 26°347.712.25.9

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 88% of the time in September, the clearest month of the year.

Beyond those clear spells, partly cloudy skies cover about 7% of September, with mostly cloudy or overcast conditions the remaining 5%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
1955
2955
3964
4964
5964
6964
7964
8964
9964
10964
11964
12964
13964
14955
15955
16955
17955
18955
19955
20955
21955
22955
23955
24955
25955
26955
27955
28946
29946
30946

Chance of precipitation in September

Any precipitation

Ilha Grande gets around 1 mm of rain over 0.2 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 1% and peaks near 2% on the wettest days.

0%10%20%30%151015202530
Rain chance (%)
10
20
30
40
50
60
70
80
90
101
111
121
131
141
151
161
171
181
191
201
211
221
231
242
252
262
272
282
292
302

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 99% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Muggy (%)Oppressive (%)
1199
2298
3298
4298
5298
6298
7298
8298
9298
10298
11298
12298
13298
14298
15298
16298
17298
18199
19199
20199
21199
22199
23199
24199
25199
26199
270100
280100
290100
300100

Wind in September

Winds average 30 km/h in September.

Across September, daily wind ranges from about 29 km/h on the calmest days to 31 km/h at its breeziest. It stays fairly steady from day to day.

0102030151015202530
Wind speed (km/h)Feels
129windy
229windy
330windy
430windy
530windy
630windy
730windy
830windy
930windy
1030windy
1130windy
1230windy
1330windy
1430windy
1530windy
1630windy
1731windy
1831windy
1931windy
2031windy
2131windy
2231windy
2331windy
2431windy
2531windy
2631windy
2731windy
2831windy
2931windy
3031windy

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 5:49 AM to 5:36 AM, and sunset from 5:45 PM to 5:37 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.95:495:45
211.95:485:45
312.05:485:45
412.05:475:45
512.05:475:44
612.05:475:44
712.05:465:44
812.05:465:43
912.05:455:43
1012.05:455:43
1112.05:445:43
1212.05:445:42
1312.05:435:42
1412.05:435:42
1512.05:435:41
1612.05:425:41
1712.05:425:41
1812.05:415:41
1912.05:415:40
2012.05:405:40
2112.05:405:40
2212.05:395:39
2312.05:395:39
2412.05:385:39
2512.05:385:39
2612.05:385:38
2712.05:375:38
2812.05:375:38
2912.05:365:37
3012.05:365:37

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.97 kWh/m².

For context, solar energy here swings from a low near 4.98 kWh/m² to a high of 7.04 kWh/m² in October across the year — September's 6.97 kWh/m² sits near the top of that range.

02468151015202530
Solar energy (kWh/m²)Level
16.8Intense
26.8Intense
36.8Intense
46.8Intense
56.8Intense
66.8Intense
76.9Intense
86.9Intense
96.9Intense
106.9Intense
116.9Intense
126.9Intense
137.0Intense
147.0Intense
157.0Intense
167.0Intense
177.0Intense
187.0Intense
197.0Intense
207.0Intense
217.0Intense
227.0Intense
237.0Intense
247.0Intense
257.0Intense
267.0Intense
277.0Intense
287.0Intense
297.1Intense
307.1Intense
Planning a trip in September

Hazard calendar for Ilha Grande

In seasonPeak

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

Ilha Grande's monsoon runs February–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 Ilha Grande?

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

7.2
Sightseeing
1st-best month of the year
9.4
Beach & pool
1st-best month of the year

September is one of the better times to visit Ilha Grande for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Ilha Grande in September

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

In September, Ilha Grande sees daytime highs around 29°C and nights near 26°C. Pack light clothes, sun protection and a windbreaker.

light clothessun protectiona windbreaker

Sea temperature near Ilha Grande in September

The nearest coast averages about 27°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 21 km away) is warmest in May at about 29°C and coldest in September near 27°C.

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

26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Tropical
Feb28Tropical
Mar29Tropical
Apr29Tropical
May29Tropical
Jun29Tropical
Jul28Warm
Aug27Warm
Sep27Warm
Oct27Warm
Nov28Warm
Dec28Tropical

UV index in Ilha Grande 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 Ilha Grande peaks around March 17 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 14 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 14UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar16Extreme
Apr14Extreme
May12Extreme
Jun10Extreme
Jul10Extreme
Aug10Extreme
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec11Extreme

Air quality in Ilha Grande 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 Ilha Grande is worst in December — around 18 µg/m³ PM2.5 (moderate), about 3.0× the cleanest month (August, 6 µg/m³).

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

01020JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateDec 1217 µg/m³Aug 216 µg/m³
PM2.5 (µg/m³)Level
Jan12Moderate
Feb15Moderate
Mar13Moderate
Apr11Good
May8Good
Jun7Good
Jul9Good
Aug6Good
Sep7Good
Oct10Good
Nov16Moderate
Dec18Moderate
Location & terrain

Where is Ilha Grande?

Ilha Grande sits at 2.9°S, 41.8°W, 0 m above sea level, in Brazil. The nearest listed city is Parnaíba, 7.0 km away.

Topography around Ilha Grande

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

Within 3 km, the terrain around Ilha Grande has only modest variations in elevation — a maximum elevation change of 24 m around an average of 4 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 45 m; within 80 km, large variations in elevation — a maximum elevation change of 656 m.

The land around Ilha Grande is covered by grassland (49%) and trees (22%) within 3 km, grassland (32%) within 16 km, and trees (38%) and water (35%) within 80 km.

3 km
24 m
16 km
45 m
80 km
656 m
treesshrubsgrasslandartificial surfacesbare terrainwaterwetlandmangroves
September weather nearby: Parnaíba 7.0 km · Araioses 10 km · Luís Correia 17 km · Buriti dos Lopes 36 km · Tutóia 52 km · Cocal 75 km · Paulino Neves 81 km · São Bernardo 88 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 Ilha Grande (-2.8521°, -41.8169°, elevation 0 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).