Climate and average weather in São Sebastião

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

Best: late May to mid December

Over the course of the year, the temperature in São Sebastião typically varies from 20°C to 32°C, and is rarely below 19°C or above 34°C. December is the hottest month of the year, while July is the coldest.

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

Hottest
Dec
32°
Coldest
Jul
21°
Wettest
May
98 mm
Driest
Dec
22 mm
Rain / yr
674 mm
171 wet days
Daylight
11.4–12.6 h
shortest–longest
Elevation
204 m
9.9°S
Clearest
Sep
51% cloud

São Sebastião is human 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 late May to mid December.

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 December, with an average high of 32°C and low of 23°C; the coolest is July, with an average low of 21°C and high of 26°C.

Days typically run about 7°C warmer than nights year-round.

15°20°25°30°35°JanFebMarAprMayJunJulAugSepOctNovDec
Avg high (°C)Avg low (°C)
Jan3124
Feb3124
Mar3124
Apr3023
May2922
Jun2721
Jul2621
Aug2720
Sep2821
Oct3022
Nov3123
Dec3223

How hot and cold São Sebastião really feels

Feels-like highFeels-like lowactual air temp

The felt-temperature range through the year — heat index on the day's high (summer humidity), wind chill on the night's low (winter wind). The dashed lines are the plain thermometer; the gap is how much hotter or colder it really feels.

On the hottest afternoons, once humidity is folded in, São Sebastião feels like about 35°C (around March 6). About 200 days a year carry some heat stress, peaking in March.

20°25°30°35°40°JanFebMarAprMayJunJulAugSepOctNovDec
Feels-like high (°C)Air high (°C)Feels-like low (°C)Air low (°C)
Jan35312324
Feb35312424
Mar35312424
Apr34302323
May31292222
Jun28272121
Jul26262121
Aug27272020
Sep30282121
Oct32302222
Nov34312323
Dec35322323

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 December afternoons, near 32°C, and coldest before dawn in July, near 21°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
Jan31° / 24°4110.912.54.2
Feb31° / 24°4511.112.34.1
Mar31° / 24°5613.312.14.1
Apr30° / 23°7516.611.84.1
May29° / 22°9819.711.64.5
Jun27° / 21°9121.511.44.8
Jul26° / 21°8622.211.54.9
Aug27° / 20°6019.411.75.3
Sep28° / 21°4213.911.95.7
Oct30° / 22°339.112.25.4
Nov31° / 23°266.412.54.9
Dec32° / 23°226.512.64.6

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 674 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 5.8 months, from around Mar 24 to Sep 16, peaking in June at about 73% chance on a given day. The drier stretch runs the rest of the year, bottoming out around Dec 3.

May is the wettest month by volume, with 98 mm over about 20 wet days; December is the driest, with 22 mm.

0%10%20%30%40%50%60%70%80%JanFebMarAprMayJunJulAugSepOctNovDecdrierwetterdriermostly drysome rainoften wetvery wetJun 12 · 73%Dec 3 · 17%
Rain on a day (%)Rain days
Jan3511
Feb4011
Mar4313
Apr5617
May6420
Jun7122
Jul7022
Aug6319
Sep4614
Oct309
Nov216
Dec227

Monthly rainfall

Over a full year, São Sebastião collects about 674 mm of rain across 171 wet days — roughly 56 mm in an average month.

It doesn’t fall evenly. May is the wettest month with 98 mm, while December is the driest at just 22 mm. The three wettest months alone bring about 41% of the year’s total.

0255075100125JanFebMarAprMayJunJulAugSepOctNovDec414556759891866042332622
Rainfall (mm)Rain days
Jan4111
Feb4511
Mar5613
Apr7517
May9820
Jun9122
Jul8622
Aug6019
Sep4214
Oct339
Nov266
Dec227

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 moderate seasonal variation over the course of the year.

The clearer part of the year begins around August 18 and lasts for 3.1 months, ending around November 19. The clearest month is September, when the sky is clear, mostly clear, or partly cloudy 72% of the time on average.

The cloudier part of the year begins around March 14 and lasts for 3.1 months, ending around June 15. The cloudiest month is May, when it is overcast or mostly cloudy 47% 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%JanFebMarAprMayJunJulAugSepOctNovDecSep 25 · 77%May 1 · 50%clearmostly clearpartly cloudymostly cloudyovercastcloudierclearercloudier
Clearer (%)Cloudier (%)
Jan5545
Feb5446
Mar5941
Apr5446
May5347
Jun5842
Jul5644
Aug6139
Sep7228
Oct6931
Nov6337
Dec5941

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 36 min of light; the shortest, around June 5, only 11 h 24 min — a swing of roughly 1 h 12 min.

12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDec
Daylight (h)Sunrise (AM)Sunset (PM)
Jan12.55:205:51
Feb12.35:315:51
Mar12.15:345:38
Apr11.85:335:20
May11.65:365:09
Jun11.45:445:09
Jul11.55:485:16
Aug11.75:405:20
Sep11.95:225:19
Oct12.25:055:18
Nov12.54:585:25
Dec12.65:055:40

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 8 sunny days a month — counting the days the sky stays clear or mostly clear — with a clear seasonal swing between 5 and 11 days.

The sunnier stretch runs 6.9 months, from around Sep 21 to Apr 18. The sunniest month is December, with roughly 10 sunny days (mixed).

The greyest month is August, down near 6 sunny days — about 44% fewer than the December peak.

051015JanFebMarAprMayJunJulAugSepOctNovDecsunniergreyersunniergloomymixedDec 1011 daysAug 175 days
Sunny daysSky
Jan9Mixed
Feb8Mixed
Mar9Mixed
Apr8Mixed
May8Gloomy
Jun7Gloomy
Jul7Gloomy
Aug6Gloomy
Sep8Gloomy
Oct9Mixed
Nov10Mixed
Dec11Mixed

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.

São Sebastião is humid all year round — on a typical day the air feels at least humid, and there is no real dry season to wait for.

The stickiest month is January, when it feels muggy, oppressive or miserable about 100% of the time. Even in January, the mildest month, the air is dry or comfortable only 0% of the time.

0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecoppressivemuggy
Humid (%)Muggy (%)Oppressive (%)Miserable (%)
Jan029710
Feb014861
Mar06921
Apr05932
May012870
Jun038620
Jul270280
Aug385120
Sep280180
Oct069300
Nov059410
Dec047530

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

The windier part of the year lasts 5.6 months, from around Sep 2 to Feb 17. The windiest month is November, averaging about 14 km/h (light breeze).

The calmer part of the year runs from around Feb 18 to Sep 1, with May the calmest month at about 9 km/h.

05101520JanFebMarAprMayJunJulAugSepOctNovDecwindiercalmerwindiercalmlight breezeNov 12 · 14 km/hMay 8 · 9 km/h
Wind speed (km/h)Feels
Jan12light breeze
Feb11calm
Mar11calm
Apr10calm
May9calm
Jun10calm
Jul10calm
Aug11calm
Sep12calm
Oct13light breeze
Nov14light breeze
Dec13light breeze

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 rainy season runs February–August, when most of the year's rain falls.

Rainy season
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 late 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 May to mid December, with a peak score in the third week of September.

0246810JanFebMarAprMayJunJulAugSepOctNovDecbest timetravel scoretemperaturecloudsprecipitationSep 17 · 5.7

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
Jan4.2fair
Feb4.1fair
Mar4.1fair
Apr4.1fair
May4.5fair
Jun4.8fair
Jul4.9fair
Aug5.2fair
Sep5.7good
Oct5.4fair
Nov4.9fair
Dec4.6fair

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 early September to mid April, with a peak score in the second week of November.

024681012JanFebMarAprMayJunJulAugSepOctNovDecbest timebest timebeach/pool scoretemperaturecloudsprecipitationNov 14 · 7.3

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 32°C. Across the year the things worth having are light clothes, sun protection and rain gear.

Light clothing
Warm layer
Winter coat
Rain gear
Sun protection
Windbreaker

In December, São Sebastião sees daytime highs around 32°C and nights near 23°C. Pack light clothes and sun protection. About 7 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 52 km away) is warmest in April at about 29°C and coldest in August near 26°C.

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

24°26°28°30°JanFebMarAprMayJunJulAugSepOctNovDecwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan28Warm
Feb28Tropical
Mar28Tropical
Apr29Tropical
May28Warm
Jun27Warm
Jul26Warm
Aug26Warm
Sep26Warm
Oct26Warm
Nov27Warm
Dec27Warm

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 22 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 23 at about 9 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highExtremeFeb 22UV 14Jun 23UV 9
UV index (midday)Level
Jan14Extreme
Feb14Extreme
Mar14Extreme
Apr13Extreme
May10Extreme
Jun9Very high
Jul9Very high
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov13Extreme
Dec12Extreme

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 6.5 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)
Jan8.56.5
Feb8.56.5
Mar86.5
Apr86
May75
Jun74.5
Jul74.5
Aug7.55
Sep7.55.5
Oct86
Nov86
Dec86
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 5,777 degree days a year, and the running total — which growers use to time plantings and predict maturity — climbs fastest around February.

02,0004,0006,000JanFebMarAprMayJunJulAugSepOctNovDec
Growing degree days (°C·days)
Jan541
Feb489
Mar541
Apr501
May479
Jun427
Jul416
Aug416
Sep433
Oct488
Nov506
Dec540

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 5.3 kWh/m² a day of solar energy on average — bright — with a clear seasonal swing between 3.8 and 6.3 kWh/m².

The brighter stretch of the year lasts 6.8 months, from around Sep 17 to Apr 10. The brightest month is December, averaging about 6.3 kWh/m² (intense).

The dimmest month is June, down near 3.9 kWh/m² — roughly 38% less than the December peak.

01234567JanFebMarAprMayJunJulAugSepOctNovDecbrighterdimmerbrighterdimmoderatebrightintenseDec 46.3 kWhJun 283.8 kWh
Solar energy (kWh/m²)Level
Jan6.1Intense
Feb6.1Intense
Mar5.8Bright
Apr5.1Bright
May4.3Bright
Jun3.9Moderate
Jul3.9Moderate
Aug4.5Bright
Sep5.3Bright
Oct5.9Bright
Nov6.3Intense
Dec6.3Intense

Where is São Sebastião?

São Sebastião sits at 9.9°S, 36.6°W, 204 m above sea level, in Brazil. The nearest listed city is Junqueiro, 9.0 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 123 m around an average of 185 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 299 m; within 80 km, large variations in elevation — a maximum elevation change of 909 m.

The land around São Sebastião is covered by grassland (68%) within 3 km, grassland (67%) and cropland (21%) within 16 km, and grassland (56%) within 80 km.

3 km
123 m
16 km
299 m
80 km
909 m
treesshrubsgrasslandcroplandartificial surfaceswaterwetland
Nearby: Junqueiro 9.0 km · Feira Grande 14 km · Teotônio Vilela 22 km · Limoeiro de Anadia 22 km · Lagoa da Canoa 23 km · Arapiraca 23 km · Igreja Nova 24 km · Campo Alegre 28 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 (-9.9336°, -36.5542°, elevation 204 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).