São Sebastião da Boa Vista weather in September

In September, São Sebastião da Boa Vista sees average daytime highs of 32°C and overnight lows near 25°C, with 18 mm of rain across 4.5 wet days and about 12 hours of daylight. It is the 2nd-warmest and 12th-wettest month of the year here.

Day-to-day highs hold fairly steady near 32°C through the month. The sky is clear or mostly clear about 64% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 hours at the start of September to 12 hours by month's end. Set against the rest of the year, September is São Sebastião da Boa Vista's 2nd-clearest and 2nd-windiest month. For the whole year in context, see São Sebastião da Boa Vista's year-round climate.

Daytime high
32°
2nd warmest
Overnight low
25°
10th coldest
Rainfall
18 mm
4.5 wet days
Daylight
12 hours
6:13 AM – 6:12 PM
Cloud cover
38%
2nd clearest
Wind
11 km/h
2nd windiest
Solar energy
6.53 kWh/m²
Travel score
4.4
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 32°C through the month.

A typical September day in São Sebastião da Boa Vista reaches about 32°C in the afternoon and slips back to 25°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 31°C and 33°C. Set against its neighbours, September runs on par with August and on par with October.

20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
13225
23225
33225
43225
53225
63225
73225
83225
93225
103225
113225
123225
133225
143225
153225
163325
173325
183325
193325
203325
213325
223325
233325
243325
253325
263325
273325
283325
293325
303325

How September really feels in São Sebastião da Boa Vista

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.

São Sebastião da Boa Vista weather by month

How September compares with the rest of the year at a glance. September is the 2nd-warmest and 12th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 24°26127.712.12.8
Feb30° / 24°34926.812.12.7
Mar30° / 24°44330.4122.6
Apr30° / 24°41729.4122.6
May31° / 25°29827.811.92.8
Jun31° / 24°13220.411.93.4
Jul31° / 24°7615.311.94.0
Aug32° / 25°348.311.94.3
Sep32° / 25°184.5124.4
Oct33° / 25°204.9124.2
Nov32° / 25°437.312.14.0
Dec32° / 25°1141712.13.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 64% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 20% of September, with mostly cloudy or overcast conditions the remaining 15%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18911
28911
38911
48812
58812
68911
78911
88812
98812
108812
118614
128614
138614
148614
158515
168416
178416
188317
198317
208218
218218
228218
238218
248218
258119
268119
278119
288119
298119
307921

Chance of precipitation in September

Any precipitation

São Sebastião da Boa Vista gets around 18 mm of rain over 4.5 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 15% and peaks near 21% on the wettest days. The odds ease toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
121
220
320
419
519
618
718
817
917
1016
1116
1216
1316
1415
1515
1615
1714
1814
1914
2014
2113
2213
2313
2413
2513
2613
2713
2813
2913
3013

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 65% of days. Sticky, muggy-or-worse air turns up on roughly 100% of them.

0%25%50%75%100%151015202530
Oppressive (%)Miserable (%)
15347
25446
35644
45743
55842
65941
76040
86139
96139
106238
116238
126337
136337
146337
156436
166535
176535
186634
196733
206832
216931
227030
237129
247228
257327
267426
277426
287525
297525
307525

Wind in September

Winds average 11 km/h in September.

Across September, daily wind ranges from about 10 km/h on the calmest days to 11 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
110calm
210calm
310calm
410calm
510calm
610calm
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1411calm
1511calm
1611calm
1711calm
1811calm
1911calm
2011calm
2111calm
2211calm
2311calm
2411calm
2511calm
2611calm
2711calm
2811calm
2911calm
3011calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 hours 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 0 minutes over September. Sunrise moves from 6:19 AM to 6:07 AM, and sunset from 6:17 PM to 6:08 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.06:196:17
212.06:186:17
312.06:186:16
412.06:186:16
512.06:176:16
612.06:176:15
712.06:166:15
812.06:166:15
912.06:166:14
1012.06:156:14
1112.06:156:14
1212.06:146:13
1312.06:146:13
1412.06:146:13
1512.06:136:12
1612.06:136:12
1712.06:126:12
1812.06:126:12
1912.06:116:11
2012.06:116:11
2112.06:116:11
2212.06:106:10
2312.06:106:10
2412.06:096:10
2512.06:096:09
2612.06:096:09
2712.06:086:09
2812.06:086:08
2912.06:076:08
3012.06:076:08

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.53 kWh/m².

For context, solar energy here swings from a low near 4.51 kWh/m² to a high of 6.65 kWh/m² in October across the year — September's 6.53 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.3Intense
26.3Intense
36.4Intense
46.4Intense
56.4Intense
66.4Intense
76.4Intense
86.4Intense
96.4Intense
106.5Intense
116.5Intense
126.5Intense
136.5Intense
146.5Intense
156.5Intense
166.5Intense
176.5Intense
186.6Intense
196.6Intense
206.6Intense
216.6Intense
226.6Intense
236.6Intense
246.6Intense
256.6Intense
266.6Intense
276.7Intense
286.7Intense
296.7Intense
306.7Intense
Planning a trip in September

Hazard calendar for São Sebastião da Boa Vista

In seasonPeak

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

São Sebastião da Boa Vista's monsoon runs January–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 São Sebastião da Boa Vista?

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

4.4
Sightseeing
1st-best month of the year
7.4
Beach & pool
1st-best month of the year

September is a reasonable time to visit São Sebastião da Boa Vista for sightseeing. The water and warmth also suit a beach or pool day.

What to pack for São Sebastião da Boa Vista in September

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

In September, São Sebastião da Boa Vista sees daytime highs around 32°C and nights near 25°C. Pack light clothes and sun protection. About 5 days see rain.

light clothessun protection

UV index in São Sebastião da Boa Vista 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 São Sebastião da Boa Vista peaks around March 14 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 24 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 14UV 15Jul 24UV 10
UV index (midday)Level
Jan13Extreme
Feb15Extreme
Mar15Extreme
Apr14Extreme
May12Extreme
Jun10Extreme
Jul10Extreme
Aug10Extreme
Sep12Extreme
Oct12Extreme
Nov10Extreme
Dec10Extreme

Air quality in São Sebastião da Boa Vista 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 São Sebastião da Boa Vista is worst in February — around 19 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (June, 9 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateFeb 2019 µg/m³Jun 239 µg/m³
PM2.5 (µg/m³)Level
Jan17Moderate
Feb19Moderate
Mar19Moderate
Apr16Moderate
May11Good
Jun9Good
Jul9Good
Aug11Good
Sep13Moderate
Oct16Moderate
Nov16Moderate
Dec15Moderate
Location & terrain

Where is São Sebastião da Boa Vista?

São Sebastião da Boa Vista sits at 1.7°S, 49.5°W, 5 m above sea level, in Brazil. The nearest listed city is Limoeiro do Ajuru, 26 km away.

Topography around São Sebastião da Boa Vista

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

Within 3 km, the terrain around São Sebastião da Boa Vista has only modest variations in elevation — a maximum elevation change of 25 m around an average of 8 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 29 m; within 80 km, only modest variations in elevation — a maximum elevation change of 40 m.

The land around São Sebastião da Boa Vista is covered by trees (60%) and water (37%) within 3 km, trees (64%) and water (33%) within 16 km, and trees (71%) within 80 km.

3 km
25 m
16 km
29 m
80 km
40 m
treesgrasslandartificial surfaceswaterwetland
September weather nearby: Limoeiro do Ajuru 26 km · Curralinho 31 km · Muaná 41 km · Oeiras do Pará 48 km · Cametá 59 km · Igarapé Miri 70 km · Abaetetuba 72 km · Bagre 78 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 da Boa Vista (-1.7146°, -49.5315°, elevation 5 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).