Climate and average weather in São Sebastião

In São Sebastião, the weather is muggy, warm, wet, and partly cloudy and remarkably steady, with daytime highs holding near warm levels all year. The wettest stretch peaks around January.

Best: early April to early November

Over the course of the year, the temperature in São Sebastião typically varies from 18°C to 27°C, and is rarely below 15°C or above 30°C. February is the hottest month of the year, while August is the coldest.

Based on the travel score, the best time of year to visit São Sebastião for warm-weather activities is from early April to early November.

Hottest
Feb
27°
Coldest
Aug
18°
Wettest
Jan
277 mm
Driest
Aug
75 mm
Rain / yr
1914 mm
181 wet days
Daylight
10.5–13.5 h
shortest–longest
Elevation
6 m
23.8°S
Clearest
Jul
48% cloud

São Sebastião is settlement in Brazil.

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

São Sebastião weather by month, at a glance

The whole year in one picture — sky, rain, humidity, temperature and travel score. Click any band to jump to its full chart.

Each stripe is one measure across the whole year, stacked so a single day reads top to bottom. The sky band runs overcast grey on top down to clear blue at the base — more blue means sunnier — followed by the rainfall curve, the humidity band, a temperature strip that tints each stretch of the year by how warm its average high is, and the travel-score line at the foot. Scan straight down any date to read that day across every measure at once; the score climbs highest around early April to early November.

Temperature through the year

Average highAverage lowShaded bands: 10–90% of days

Daily average highs and lows in São Sebastião, from 1991–2020 of climate data. The shaded bands show the range most days fall in — 10th to 90th percentile.

Temperatures in São Sebastião stay fairly even through the year, without a distinct hot or cool season. The warmest month is February, with an average high of 27°C and low of 24°C; the coolest is August, with an average low of 18°C and high of 22°C.

Days typically run about 4°C warmer than nights year-round.

10°15°20°25°30°35°JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)Avg low (°C)
Jan2724
Feb2724
Mar2723
Apr2522
May2320
Jun2318
Jul2218
Aug2218
Sep2219
Oct2320
Nov2421
Dec2622

Average hourly temperature in São Sebastião

A compact picture of the whole year, hour by hour: each column is a day, each row an hour, and the color is the modeled average temperature. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.

Read left to right for the day of the year and top to bottom for the hour of the day; the color is the modeled temperature, cool blues through to hot reds on the same scale as the other charts. A vertical slice is a single day's swing — coolest just before dawn, warmest in the mid-afternoon — while a horizontal slice follows one hour across the seasons. The darker overlay marks night and the lighter one the twilight around sunrise and sunset. Colors run warmest on February afternoons, near 27°C, and coldest before dawn in August, near 18°C.

JanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM

São Sebastião weather by month

Every month at a glance. Click a month for its detailed page.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan27° / 24°27722.413.34.6
Feb27° / 24°22819.612.84.7
Mar27° / 23°23620.612.25.0
Apr25° / 22°13013.711.56.2
May23° / 20°11512.110.96.6
Jun23° / 18°829.510.67.0
Jul22° / 18°928.810.77.0
Aug22° / 18°758.911.27.0
Sep22° / 19°13213.711.96.1
Oct23° / 20°14715.212.65.8
Nov24° / 21°18717.513.15.6
Dec26° / 22°21419.213.45.1

Chance of rain

How likely it is to rain on a typical day, and how that shifts across the wetter and drier seasons.

São Sebastião gets about 1914 mm of precipitation a year. On a typical day the chance of rain is very wet, but that rises and falls sharply with the seasons.

The wetter season lasts 5.7 months, from around Oct 17 to Apr 9, peaking in January at about 72% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Aug 15.

January is the wettest month by volume, with 277 mm over about 22 wet days; August is the driest, with 75 mm.

0%10%20%30%40%50%60%70%80%JanFebMarAprMayJunJulAugSepOctNovDecwetterdrierwettermostly drysome rainoften wetvery wetJan 24 · 72%Aug 15 · 28%
Rain on a day (%)Rain days
Jan7122
Feb7020
Mar6621
Apr4614
May4012
Jun3110
Jul299
Aug299
Sep4414
Oct5115
Nov5718
Dec6319

Monthly rainfall

Over a full year, São Sebastião collects about 1914 mm of rain across 181 wet days — roughly 160 mm in an average month.

It doesn’t fall evenly. January is the wettest month with 277 mm, while August is the driest at just 75 mm. The three wettest months alone bring about 39% of the year’s total.

050100150200250300JanFebMarAprMayJunJulAugSepOctNovDec277228236130115829275132147187214
Rainfall (mm)Rain days
Jan27722
Feb22820
Mar23621
Apr13014
May11512
Jun8210
Jul929
Aug759
Sep13214
Oct14715
Nov18718
Dec21419

Clouds and sunshine

ClearMostly clearPartly cloudyMostly cloudyOvercast

How often the daytime sky is clear, partly cloudy or overcast.

In São Sebastião, the average share of the sky covered by clouds shows significant seasonal variation over the course of the year.

The clearer part of the year begins around March 22 and lasts for 5.7 months, ending around September 12. The clearest month is June, when the sky is clear, mostly clear, or partly cloudy 58% of the time on average.

The cloudier part of the year begins around September 13 and lasts for 6.2 months, ending around March 21. The cloudiest month is December, when it is overcast or mostly cloudy 72% of the time.

0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%JanFebMarAprMayJunJulAugSepOctNovDecApr 29 · 60%Dec 7 · 26%clearmostly clearpartly cloudymostly cloudyovercastcloudierclearercloudier
Clearer (%)Cloudier (%)
Jan3070
Feb3565
Mar4357
Apr5545
May5545
Jun5842
Jul5644
Aug5644
Sep4159
Oct3070
Nov3070
Dec2872

Daylight, sunrise and sunset

DaylightNight

Hours of daylight through the year, with sunrise and sunset times.

The gold band is daylight — sunrise runs along its lower edge, sunset along the upper — so it widens toward summer and pinches toward winter, with night the dark area above and below. The longest day, around December 14, brings about 13 h 30 min of light; the shortest, around June 15, only 10 h 30 min — a swing of roughly 3 hours.

12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDec
Daylight (h)Sunrise (AM)Sunset (PM)
Jan13.36:317:50
Feb12.86:527:41
Mar12.27:067:16
Apr11.57:186:45
May10.97:326:24
Jun10.67:466:18
Jul10.77:476:27
Aug11.27:316:41
Sep11.97:006:52
Oct12.66:307:04
Nov13.16:127:22
Dec13.46:147:42

Sunny days

How many genuinely sunny days each month brings — days the sky stays clear or mostly clear — banded into plain-language zones.

São Sebastião averages about 9 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 4 and 14 days.

The sunnier stretch runs 5.3 months, from around Apr 8 to Sep 15. The sunniest month is August, with roughly 14 sunny days (mixed).

The greyest month is January, down near 5 sunny days — about 67% fewer than the August peak.

05101520JanFebMarAprMayJunJulAugSepOctNovDecgreyersunniergreyergloomymixedbrightAug 2314 daysJan 24 days
Sunny daysSky
Jan5Gloomy
Feb5Gloomy
Mar7Gloomy
Apr10Mixed
May12Mixed
Jun13Mixed
Jul14Mixed
Aug14Mixed
Sep9Mixed
Oct5Gloomy
Nov5Gloomy
Dec4Gloomy

Humidity comfort

DryComfortableHumidMuggyOppressiveMiserable

Share of days at each humidity comfort level, based on the dew point — the measure that tracks how muggy it actually feels.

Humidity comfort is graded by the dew point — the temperature at which the air would be fully saturated — because it tracks how muggy it actually feels far better than relative humidity does. A low dew point feels dry and crisp; a high one feels sticky and oppressive no matter the reading on a humidity gauge.

In São Sebastião, how humid it feels changes noticeably over the year.

The more humid part of the year lasts 6.8 months, from around October 14 to May 7. The muggiest month is January, when the air feels humid, muggy or worse about 100% of the time.

The most comfortable stretch runs from around May 8 to October 13, and July is the most comfortable month — the air is dry or comfortable 26% of the time.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJul 19 · 29%Jan 1 · 0%miserablehumidmuggyoppressivecomfortablehumidcomfortablehumid
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
Jan002176614
Feb002156716
Mar00424648
Apr021639422
May211354470
Jun413493300
Jul718601500
Aug717542200
Sep313424020
Oct192551140
Nov051946290
Dec00831574

Wind

Average wind speed through the year, banded into plain-language speed zones so a number reads as 'breezy' or 'calm' without knowing the scale.

This is the average sustained wind speed at the standard 10 metres above open ground — the steady flow a weather station reports, not the sharper gusts that come and go, which can run half again as fast. It's the number that says whether a place is generally breezy or calm.

Across the year, average wind speed in São Sebastião is typically calm, near 10 km/h, and varies little with the seasons.

The windier part of the year lasts 5.2 months, from around Jul 11 to Dec 14. The windiest month is September, averaging about 11 km/h (calm).

The calmer part of the year runs from around Dec 15 to Jul 10, with February the calmest month at about 8 km/h.

051015JanFebMarAprMayJunJulAugSepOctNovDeccalmerwindiercalmlight breezeSep 26 · 11 km/hFeb 13 · 8 km/h
Wind speed (km/h)Feels
Jan9calm
Feb8calm
Mar9calm
Apr9calm
May9calm
Jun9calm
Jul10calm
Aug10calm
Sep11calm
Oct11calm
Nov11calm
Dec10calm

Best time to visit São Sebastião

TravelBeach/poolTemperatureCloudsPrecipitation

To characterize how pleasant the weather is in São Sebastião throughout the year, we compute two travel scores — one for general sightseeing, one for beach and pool weather.

Around late October, São Sebastião is still near the tail of its best-weather window — great conditions with the peak-season crowds already thinning.

Inferred from the travel-score curve; month-by-month visitor numbers are a planned addition.

The travel score favors clear, rainless days with daytime highs between 18°C and 28°C. Based on this score, the best time of year to visit São Sebastião for general outdoor tourist activities is from early April to late October, with a peak score in the third week of June.

0246810JanFebMarAprMayJunJulAugSepOctNovDecbest timetravel scoretemperaturecloudsprecipitationJun 20 · 7.1

The travel score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Travel score (0–10)Rating
Jan4.6fair
Feb4.7fair
Mar5.0fair
Apr6.2good
May6.6good
Jun7.0good
Jul7.0good
Aug6.9good
Sep6.1good
Oct5.8good
Nov5.6good
Dec5.1fair

The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best times of year to visit São Sebastião for hot-weather activities run from late January to mid July and again from mid November to early January, with a peak score in the last week of April.

024681012JanFebMarAprMayJunJulAugSepOctNovDecbest timebest timebeach/pool scoretemperaturecloudsprecipitationApr 24 · 5.9

The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

What to pack for São Sebastião, by month

EssentialRecommendedOptional

Month by month, what's worth putting in the bag — from the temperature range, rain chance, sun and wind. Tap a month for a quick packing note.

São Sebastião packs about the same all year — highs hold near 27°C. Across the year the things worth having are light clothes, rain gear and sun protection.

Light clothing
Warm layer
Winter coat
Rain gear
Sun protection
Windbreaker

In February, São Sebastião sees daytime highs around 27°C and nights near 24°C. Pack light clothes and rain gear. Worth having: sun protection. About 20 days see rain.

Sea temperature near São Sebastião

Average ocean temperature at the nearest coast, month by month, banded into swim-comfort zones — the other half of the beach question.

The sea at the nearest coast (about 25 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°25°JanFebMarAprMayJunJulAugSepOctNovDeccoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan26Warm
Feb27Warm
Mar27Warm
Apr26Warm
May24Refreshing
Jun22Refreshing
Jul21Refreshing
Aug21Refreshing
Sep21Refreshing
Oct22Refreshing
Nov23Refreshing
Dec25Warm

UV index (midday) in São Sebastião by month

LowModerateHighVery highExtreme

Clear-sky midday UV index through the year, shaded by the WHO exposure levels — how much sun protection each month calls for.

Under clear skies, the midday UV index in São Sebastião peaks around February 8 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 11 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 8UV 14Jul 11UV 5
UV index (midday)Level
Jan14Extreme
Feb14Extreme
Mar11Extreme
Apr9Very high
May7High
Jun6High
Jul5High
Aug8Very high
Sep8Very high
Oct11Extreme
Nov13Extreme
Dec14Extreme

Average hourly UV index in São Sebastião

LowModerateHighVery highExtreme

Modeled clear-sky UV for every hour of every day — when in the day sun protection actually matters.

The whole year hour by hour: each column is a day, each row an hour, and the color is the modeled clear-sky UV index — the midday peak scaled down as the sun sits lower in the sky. Darker overlays mark night, lighter ones the civil-twilight hours around sunrise and sunset.

UV falls off far faster than brightness as the sun drops, so even in February the burn window is concentrated in the middle of the day: about 8.5 hours a day reach index 3 (protection recommended), and 7 hours reach 6 or more. Mornings and late afternoons stay comparatively gentle year round.

JanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AM
UV ≥ 3 (h/day)UV ≥ 6 (h/day)
Jan97
Feb8.57
Mar85.5
Apr74.5
May62.5
Jun50
Jul50
Aug63.5
Sep74
Oct86
Nov8.56.5
Dec97

Air quality in São Sebastião by month

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see which months the air is worst, not just the yearly average.

Air quality in São Sebastião is worst in June — around 23 µg/m³ PM2.5 (moderate), about 1.8× the cleanest month (November, 13 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateJun 2223 µg/m³Nov 2313 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr14Moderate
May18Moderate
Jun23Moderate
Jul23Moderate
Aug22Moderate
Sep21Moderate
Oct16Moderate
Nov13Moderate
Dec13Moderate
Almanac & agriculture

Growing season

Chance of a frost-free dayFrost-free year round

São Sebastião is frost-free year round — even the coldest nights rarely reach freezing, so there is no start or end to the growing season.

0%25%50%75%100%JanFebMarAprMayJunJulAugSepOctNovDecfrost-free year round
Frost-free chance (%)Frost nights
Jan1000
Feb1000
Mar1000
Apr1000
May1000
Jun1000
Jul1000
Aug1000
Sep1000
Oct1000
Nov1000
Dec1000

Growing degree days

Degree days (base 10°C)Frost-free shaded

Growing degree days tally heat above 10°C: each day adds however many degrees its average temperature runs over that threshold, and cold days add nothing. São Sebastião banks about 4,504 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around February.

01,0002,0003,0004,000JanFebMarAprMayJunJulAugSepOctNovDec
Growing degree days (°C·days)
Jan472
Feb433
Mar457
Apr402
May352
Jun312
Jul301
Aug303
Sep312
Oct354
Nov372
Dec436

Solar energy

Average daily shortwave solar energy reaching the ground, banded into brightness zones so the number means something at a glance.

Solar energy is how much sunlight actually reaches the ground each day, measured in kilowatt-hours per square metre (kWh/m²) — the combined effect of how long the sun is up, how high it climbs, and how much cloud gets in the way. It's the raw fuel a solar panel has to work with: for scale, 1 kWh/m² a day is dim and wintry, while 7+ is desert-bright.

São Sebastião receives about 4.7 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.2 and 5.9 kWh/m².

The brighter stretch of the year lasts 6.1 months, from around Sep 29 to Apr 1. The brightest month is December, averaging about 5.8 kWh/m² (bright).

The dimmest month is June, down near 3.2 kWh/m² — roughly 45% less than the December peak.

01234567JanFebMarAprMayJunJulAugSepOctNovDecbrighterdimmerbrighterdimmoderatebrightintenseDec 215.9 kWhJun 243.2 kWh
Solar energy (kWh/m²)Level
Jan5.7Bright
Feb5.7Bright
Mar5.0Bright
Apr4.4Bright
May3.5Moderate
Jun3.2Moderate
Jul3.4Moderate
Aug4.1Bright
Sep4.5Bright
Oct5.1Bright
Nov5.6Bright
Dec5.9Bright

Where is São Sebastião?

São Sebastião sits at 23.8°S, 45.4°W, 6 m above sea level, in Brazil. The nearest listed city is Ilhabela, 6.0 km away.

Topography around São Sebastião

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

Within 3 km, the terrain around São Sebastião has large variations in elevation — a maximum elevation change of 806 m around an average of 181 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,359 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,647 m.

The land around São Sebastião is covered by trees (50%) and water (39%) within 3 km, trees (53%) and water (36%) within 16 km, and water (53%) and trees (33%) within 80 km.

3 km
806 m
16 km
1,359 m
80 km
1,647 m
treesgrasslandartificial surfaceswater
Nearby: Ilhabela 6.0 km · Caraguatatuba 16 km · Paraibuna 49 km · Ubatuba 50 km · Salesópolis 52 km · Biritiba Mirim 67 km · Guararema 74 km · Bertioga 75 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 Sebastião (-23.76°, -45.4097°, elevation 6 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).