Climate and average weather in São Sebastião

In São Sebastião, the weather is hot, wet, and mostly clear and remarkably steady, with daytime highs holding near hot levels all year. The wettest stretch peaks around December.

Best: late April to late August

Over the course of the year, the temperature in São Sebastião typically varies from 14°C to 30°C, and is rarely below 12°C or above 34°C. September is the hottest month of the year, while June is the coldest.

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

Hottest
Sep
30°
Coldest
Jun
14°
Wettest
Dec
225 mm
Driest
Jul
0 mm
Rain / yr
1198 mm
138 wet days
Daylight
11.1–12.9 h
shortest–longest
Elevation
1,048 m
15.9°S
Clearest
Aug
28% cloud

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 late April to late August.

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 September, with an average high of 30°C and low of 18°C; the coolest is June, with an average low of 14°C and high of 27°C.

Days typically run about 11°C warmer than nights, with the widest day–night swing (around 13°C) in August.

10°15°20°25°30°35°JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)Avg low (°C)
Jan2819
Feb2819
Mar2819
Apr2818
May2716
Jun2714
Jul2714
Aug2915
Sep3018
Oct3019
Nov2819
Dec2819

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 September afternoons, near 30°C, and coldest before dawn in June, near 14°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
Jan28° / 19°2032112.84.6
Feb28° / 19°16018.212.54.8
Mar28° / 19°18120.112.14.8
Apr28° / 18°7111.311.76.1
May27° / 16°173.211.37.7
Jun27° / 14°40.611.18.4
Jul27° / 14°0011.18.6
Aug29° / 15°51.211.57.5
Sep30° / 18°284.811.95.6
Oct30° / 19°10413.312.44.6
Nov28° / 19°20121.212.74.3
Dec28° / 19°22523.212.94.3

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 1198 mm of precipitation a year. On a typical day the chance of rain is often wet, but that rises and falls sharply with the seasons.

The wetter season lasts 6.1 months, from around Oct 13 to Apr 16, peaking in December at about 78% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Jul 4.

December is the wettest month by volume, with 225 mm over about 23 wet days; July is the driest, with 0 mm.

0%10%20%30%40%50%60%70%80%90%JanFebMarAprMayJunJulAugSepOctNovDecwetterdrierwettermostly drysome rainoften wetvery wetDec 5 · 78%Jul 4 · 0%
Rain on a day (%)Rain days
Jan6821
Feb6518
Mar6520
Apr3711
May113
Jun21
Jul00
Aug41
Sep175
Oct4313
Nov7021
Dec7423

Monthly rainfall

Over a full year, São Sebastião collects about 1198 mm of rain across 138 wet days — roughly 100 mm in an average month.

It doesn’t fall evenly. December is the wettest month with 225 mm, while July is the driest at just 0 mm. The three wettest months alone bring about 52% of the year’s total.

050100150200250JanFebMarAprMayJunJulAugSepOctNovDec203160181711740528104201225
Rainfall (mm)Rain days
Jan20321
Feb16018
Mar18120
Apr7111
May173
Jun41
Jul00
Aug51
Sep285
Oct10413
Nov20121
Dec22523

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 April 11 and lasts for 6.1 months, ending around October 14. The clearest month is August, when the sky is clear, mostly clear, or partly cloudy 85% of the time on average.

The cloudier part of the year begins around October 15 and lasts for 5.8 months, ending around April 10. The cloudiest month is December, when it is overcast or mostly cloudy 80% 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%JanFebMarAprMayJunJulAugSepOctNovDecAug 16 · 86%Dec 7 · 17%clearmostly clearpartly cloudymostly cloudyovercastcloudierclearercloudier
Clearer (%)Cloudier (%)
Jan2575
Feb3169
Mar3664
Apr5743
May6733
Jun7822
Jul8416
Aug8515
Sep7228
Oct4852
Nov2476
Dec2080

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 January 1, brings about 12 h 54 min of light; the shortest, around May 29, only 11 h 06 min — a swing of roughly 1 h 48 min.

12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDec
Daylight (h)Sunrise (AM)Sunset (PM)
Jan12.86:557:46
Feb12.57:107:42
Mar12.17:177:24
Apr11.77:227:01
May11.37:306:45
Jun11.17:406:43
Jul11.17:436:51
Aug11.57:316:59
Sep11.97:087:03
Oct12.46:457:07
Nov12.76:347:19
Dec12.96:397:35

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 11 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 2 and 22 days.

The sunnier stretch runs 5.8 months, from around Apr 18 to Oct 11. The sunniest month is August, with roughly 21 sunny days (bright).

The greyest month is December, down near 3 sunny days — about 86% fewer than the August peak.

0510152025JanFebMarAprMayJunJulAugSepOctNovDecgreyersunniergreyergloomymixedbrightbrilliantAug 822 daysDec 32 days
Sunny daysSky
Jan4Gloomy
Feb4Gloomy
Mar6Gloomy
Apr10Mixed
May14Mixed
Jun18Bright
Jul21Bright
Aug22Bright
Sep16Bright
Oct9Mixed
Nov3Gloomy
Dec3Gloomy

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 dramatically over the year.

The more humid part of the year lasts 6.4 months, from around October 19 to May 2. The muggiest month is March, when the air feels humid, muggy or worse about 98% of the time.

The most comfortable stretch runs from around May 3 to October 18, and July is the most comfortable month — the air is dry or comfortable 100% of the time.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJul 15 · 100%Mar 18 · 2%muggycomfortablehumiddryhumidcomfortablehumid
Dry (%)Comfortable (%)Humid (%)Muggy (%)
Jan072964
Feb033363
Mar022969
Apr1144342
May1445365
Jun553680
Jul861400
Aug871030
Sep5822182
Oct22213621
Nov2103256
Dec062668

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 8 km/h, and varies little with the seasons.

The windier part of the year lasts 5.0 months, from around May 22 to Oct 20. The windiest month is August, averaging about 10 km/h (calm).

The calmer part of the year runs from around Oct 21 to May 21, with March the calmest month at about 7 km/h.

051015JanFebMarAprMayJunJulAugSepOctNovDeccalmerwindiercalmercalmlight breezeAug 19 · 10 km/hMar 2 · 6 km/h
Wind speed (km/h)Feels
Jan7calm
Feb7calm
Mar7calm
Apr7calm
May8calm
Jun9calm
Jul9calm
Aug10calm
Sep9calm
Oct8calm
Nov7calm
Dec7calm

Hazard calendar for São Sebastião

In seasonPeak

When the seasonal hazards worth planning around — the rainy season, tropical-cyclone risk and dust haze — are active through the year.

São Sebastião's monsoon runs October–March, when most of the year's rain falls.

Monsoon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

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 early May, São Sebastião is still near the start of its best-weather window — great conditions with the peak-season crowds not yet at full swing.

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 late April to late August, with a peak score in the first week of July.

0246810JanFebMarAprMayJunJulAugSepOctNovDecbest timetravel scoretemperaturecloudsprecipitationJul 6 · 8.7

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
Feb4.8fair
Mar4.8fair
Apr6.1good
May7.6ideal
Jun8.4ideal
Jul8.6ideal
Aug7.5good
Sep5.6good
Oct4.6fair
Nov4.3fair
Dec4.3fair

The beach/pool score favors clear, rainless days with daytime highs between 24°C and 34°C. Based on this score, the best time of year to visit São Sebastião for hot-weather activities is from late April to late September, with a peak score in the second week of August.

024681012JanFebMarAprMayJunJulAugSepOctNovDecbest timebeach/pool scoretemperaturecloudsprecipitationAug 10 · 8.9

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 30°C. Across the year the things worth having are light clothes and sun protection.

Light clothing
Warm layer
Winter coat
Rain gear
Sun protection
Windbreaker

In September, São Sebastião sees daytime highs around 30°C and nights near 18°C. Pack light clothes and sun protection. About 5 days see rain.

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 15 at about 16 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 23 at about 8 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highExtremeFeb 15UV 16Jun 23UV 8
UV index (midday)Level
Jan15Extreme
Feb16Extreme
Mar15Extreme
Apr12Extreme
May10Very high
Jun8Very high
Jul8Very high
Aug10Very high
Sep13Extreme
Oct13Extreme
Nov15Extreme
Dec13Extreme

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)
Jan8.57
Feb8.57
Mar86.5
Apr7.55.5
May74.5
Jun6.54
Jul6.54
Aug7.55
Sep86
Oct86.5
Nov8.57
Dec8.56.5

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 September — around 32 µg/m³ PM2.5 (moderate), about 2.8× the cleanest month (January, 11 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateSep 1830 µg/m³Jan 1511 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb13Moderate
Mar15Moderate
Apr14Moderate
May15Moderate
Jun13Moderate
Jul13Moderate
Aug15Moderate
Sep32Moderate
Oct21Moderate
Nov13Moderate
Dec12Moderate
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 4,656 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around October.

01,0002,0003,0004,0005,000JanFebMarAprMayJunJulAugSepOctNovDec
Growing degree days (°C·days)
Jan415
Feb377
Mar416
Apr390
May362
Jun313
Jul321
Aug367
Sep421
Oct453
Nov407
Dec415

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 5.4 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 4.6 and 6.2 kWh/m².

The brighter stretch of the year lasts 3.5 months, from around Aug 7 to Nov 20. The brightest month is October, averaging about 6.1 kWh/m² (intense).

The dimmest month is June, down near 4.6 kWh/m² — roughly 24% less than the October peak.

01234567JanFebMarAprMayJunJulAugSepOctNovDecdimmerbrighterdimmerdimmoderatebrightintenseOct 106.2 kWhJun 84.6 kWh
Solar energy (kWh/m²)Level
Jan5.6Bright
Feb5.8Bright
Mar5.3Bright
Apr5.1Bright
May4.8Bright
Jun4.6Bright
Jul4.9Bright
Aug5.6Bright
Sep6.1Intense
Oct6.1Intense
Nov5.5Bright
Dec5.5Bright

Where is São Sebastião?

São Sebastião sits at 15.9°S, 47.8°W, 1,048 m above sea level, in Brazil. The nearest listed city is Jardim Botânico, 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 only modest variations in elevation — a maximum elevation change of 233 m around an average of 968 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 343 m; within 80 km, large variations in elevation — a maximum elevation change of 779 m.

The land around São Sebastião is covered by grassland (34%), artificial surfaces (31%) and trees (23%) within 3 km, grassland (39%), trees (24%) and shrubs (21%) within 16 km, and grassland (34%), trees (25%) and cropland (22%) within 80 km.

3 km
233 m
16 km
343 m
80 km
779 m
treesshrubsgrasslandcroplandartificial surfacesbare terrainwater
Nearby: Jardim Botânico 6.0 km · Lago Sul 13 km · Paranoá 14 km · Plano Piloto 17 km · Itapoã 17 km · Park Way 18 km · Sudoeste/Octagonal 20 km · Lago Norte 20 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 (-15.9029°, -47.7761°, elevation 1,048 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. 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).