Fortuna weather in September

In September, Fortuna sees average daytime highs of 35°C and overnight lows near 23°C, with 13 mm of rain across 1.7 wet days and about 12 hours of daylight. It is the 1st-warmest and 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near 35°C through the month. The sky is clear or mostly clear about 65% of the time in September, and the air most often feels humid.

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 Fortuna's 2nd-clearest and 4th-windiest month. For the whole year in context, see Fortuna's year-round climate.

Daytime high
35°
1st warmest
Overnight low
23°
10th coldest
Rainfall
13 mm
1.7 wet days
Daylight
12 hours
5:52 AM – 5:50 PM
Cloud cover
34%
2nd clearest
Wind
9 km/h
4th windiest
Solar energy
6.43 kWh/m²
Travel score
3.2
out of 10

Fortuna is human settlement in Brazil.

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 35°C through the month.

A typical September day in Fortuna reaches about 35°C in the afternoon and slips back to 23°C overnight — a 12°C spread between the day's warmth and the night's chill. On most days the high lands between 33°C and 37°C. Set against its neighbours, September runs about 1°C warmer than August and on par with October.

20°25°30°35°40°151015202530
Avg high (°C)Avg low (°C)
13523
23523
33523
43523
53523
63523
73523
83523
93523
103523
113523
123523
133523
143523
153523
163523
173523
183523
193523
203523
213523
223523
233523
243523
253523
263523
273523
283523
293523
303523

How September really feels in Fortuna

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.

Fortuna weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 22°2342612.32.9
Feb30° / 22°22024.312.22.9
Mar30° / 22°24827.6122.8
Apr31° / 22°17321.911.93.3
May31° / 22°7311.511.74.2
Jun32° / 22°8211.74.8
Jul33° / 22°70.711.74.7
Aug34° / 22°10.211.84.0
Sep35° / 23°131.7123.2
Oct35° / 23°304.612.13.1
Nov33° / 23°9111.912.33.2
Dec32° / 23°13717.612.33.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 65% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 23% of September, with mostly cloudy or overcast conditions the remaining 12%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18911
28911
38911
48911
58911
68911
78911
88911
98911
108911
118911
128911
138911
148911
158812
168812
178812
188812
198812
208713
218713
228713
238713
248614
258614
268614
278515
288416
298416
308317

Chance of precipitation in September

Any precipitation

Fortuna gets around 13 mm of rain over 1.7 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 6% and peaks near 9% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
12
23
33
43
53
64
74
84
94
104
114
124
135
145
155
165
176
186
196
207
217
227
238
248
258
269
279
289
299
309

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels humid — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the humid band about 37% of days. Sticky, muggy-or-worse air turns up on roughly 46% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
112346237
212346238
312345238
412345238
512345238
612245238
712245249
812244249
912244259
1012144269
1112143279
1212042289
1311942299
1411941319
15018403210
16017393310
17016383511
18015373612
19014353812
20014343913
21013324114
22012314215
23011294416
24010284517
2509274518
2608264619
2708264620
2807254621
2907254622
3006244723

Wind in September

Winds average 9 km/h in September.

Across September, daily wind ranges from about 8 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
19calm
29calm
39calm
49calm
59calm
69calm
79calm
89calm
99calm
109calm
119calm
129calm
139calm
149calm
159calm
169calm
179calm
189calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

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 6:00 AM to 5:45 AM, and sunset from 5:53 PM to 5:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.96:005:53
211.95:595:53
311.95:595:53
411.95:585:52
511.95:585:52
611.95:575:52
711.95:575:52
811.95:565:52
911.95:565:51
1011.95:555:51
1111.95:555:51
1211.95:545:51
1312.05:535:51
1412.05:535:50
1512.05:525:50
1612.05:525:50
1712.05:515:50
1812.05:515:50
1912.05:505:49
2012.05:505:49
2112.05:495:49
2212.05:495:49
2312.05:485:49
2412.05:485:48
2512.05:475:48
2612.05:475:48
2712.05:465:48
2812.05:465:48
2912.05:455:47
3012.05:455:47

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.43 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.46 kWh/m² to a high of 6.43 kWh/m² in September across the year — September's 6.43 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
106.4Intense
116.4Intense
126.4Intense
136.4Intense
146.5Intense
156.5Intense
166.5Intense
176.5Intense
186.5Intense
196.5Intense
206.5Intense
216.5Intense
226.4Intense
236.4Intense
246.4Intense
256.4Intense
266.4Intense
276.4Intense
286.4Intense
296.4Intense
306.4Intense
Planning a trip in September

Hazard calendar for Fortuna

In seasonPeak

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

Fortuna's monsoon runs December–April, 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 Fortuna?

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

3.2
Sightseeing
6th-best month of the year
6.8
Beach & pool
4th-best month of the year

September is a weaker month for outdoor sightseeing in Fortuna. The water and warmth also suit a beach or pool day.

What to pack for Fortuna in September

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

In September, Fortuna sees daytime highs around 35°C and nights near 23°C. Pack light clothes and sun protection.

light clothessun protection

UV index in Fortuna 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 Fortuna peaks around March 11 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near August 10 at about 10 (very high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highExtremeMar 11UV 15Aug 10UV 10
UV index (midday)Level
Jan13Extreme
Feb15Extreme
Mar15Extreme
Apr14Extreme
May11Extreme
Jun10Very high
Jul10Very high
Aug10Very high
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec11Extreme

Air quality in Fortuna 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 Fortuna is worst in October — around 53 µg/m³ PM2.5 (poor), about 8.4× the cleanest month (June, 6 µg/m³).

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

0204060JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModeratePoorModerateOct 953 µg/m³Jun 167 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar12Good
Apr11Good
May8Good
Jun6Good
Jul8Good
Aug25Moderate
Sep53Poor
Oct53Poor
Nov23Moderate
Dec17Moderate
Location & terrain

Where is Fortuna?

Fortuna sits at 5.7°S, 44.2°W, 210 m above sea level, in Brazil. The nearest listed city is São Domingos do Maranhão, 31 km away.

Topography around Fortuna

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

Within 3 km, the terrain around Fortuna has only modest variations in elevation — a maximum elevation change of 108 m around an average of 211 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 278 m; within 80 km, significant variations in elevation — a maximum elevation change of 410 m.

The land around Fortuna is covered by grassland (56%) and trees (35%) within 3 km, trees (59%) and grassland (32%) within 16 km, and trees (68%) and grassland (27%) within 80 km.

3 km
108 m
16 km
278 m
80 km
410 m
treesshrubsgrasslandcroplandartificial surfaces
September weather nearby: São Domingos do Maranhão 31 km · Colinas 34 km · Buriti Bravo 38 km · Presidente Dutra 61 km · Passagem Franca 65 km · Mirador 74 km · Tuntum 76 km · São João do Soter 79 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 Fortuna (-5.7333°, -44.1583°, elevation 210 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).