Ulianópolis weather in September

In September, Ulianópolis sees average daytime highs of 35°C and overnight lows near 23°C, with 11 mm of rain across 2 wet days and about 12 hours of daylight. It is the 1st-warmest and 11th-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 52% of the time in September, and the air most often feels muggy.

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 Ulianópolis's 3rd-clearest and 1st-windiest month. For the whole year in context, see Ulianópolis's year-round climate.

Daytime high
35°
1st warmest
Overnight low
23°
9th coldest
Rainfall
11 mm
2 wet days
Daylight
12 hours
6:05 AM – 6:04 PM
Cloud cover
43%
3rd clearest
Wind
10 km/h
1st windiest
Solar energy
6.12 kWh/m²
Travel score
3.2
out of 10

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 Ulianópolis 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 36°C. Set against its neighbours, September runs on par with 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
273524
283524
293524
303524

How September really feels in Ulianópolis

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.

Ulianópolis weather by month

How September compares with the rest of the year at a glance. September is the 1st-warmest and 11th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan31° / 23°23925.812.22.7
Feb30° / 23°27325.712.12.7
Mar30° / 23°34829.2122.6
Apr30° / 23°2472711.92.7
May31° / 23°13119.611.83.4
Jun32° / 22°327.411.84.3
Jul33° / 22°163.611.83.9
Aug35° / 22°61.111.93.4
Sep35° / 23°112123.2
Oct35° / 24°255.612.13.0
Nov34° / 24°6710.212.23.0
Dec33° / 23°12916.812.23.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 52% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 31% of September, with mostly cloudy or overcast conditions the remaining 17%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
18812
28713
38713
48713
58713
68713
78713
88713
98614
108614
118614
128614
138515
148515
158515
168416
178416
188317
198317
208218
218119
228119
238119
247921
257921
267921
277723
287723
297723
307525

Chance of precipitation in September

Any precipitation

Ulianópolis gets around 11 mm of rain over 2 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 7% and peaks near 11% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%151015202530
Rain chance (%)
14
24
34
44
55
65
75
85
95
105
116
126
136
146
157
167
177
187
198
208
218
229
239
249
2510
2610
2710
2810
2911
3011

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the muggy band about 54% of days. Sticky, muggy-or-worse air turns up on roughly 97% of them.

0%25%50%75%100%151015202530
Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
1145342
2045442
3045442
4045442
5045442
6045541
7045541
8045640
9045640
10045640
11045640
12045640
13045640
14035740
15035740
16035740
17035641
18035641
19035542
20035443
21025543
22025444
23025345
24025345
25015346
26015247
27015247
28015148
29015148
30015148

Wind in September

Winds average 10 km/h in September, the windiest month of the year.

Across September, daily wind ranges from about 9 km/h on the calmest days to 10 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
19calm
29calm
39calm
410calm
510calm
610calm
710calm
810calm
910calm
1010calm
1110calm
1210calm
1310calm
1410calm
1510calm
1610calm
1710calm
1810calm
1910calm
2010calm
2110calm
2210calm
2310calm
2410calm
259calm
269calm
279calm
289calm
299calm
309calm

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 6:12 AM to 5:58 AM, and sunset from 6:08 PM to 6:00 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.96:126:08
211.96:116:07
311.96:116:07
411.96:116:07
511.96:106:07
611.96:106:06
711.96:096:06
812.06:096:06
912.06:086:06
1012.06:086:05
1112.06:076:05
1212.06:076:05
1312.06:066:04
1412.06:066:04
1512.06:056:04
1612.06:056:04
1712.06:046:03
1812.06:046:03
1912.06:036:03
2012.06:036:03
2112.06:036:02
2212.06:026:02
2312.06:026:02
2412.06:016:02
2512.06:016:01
2612.06:006:01
2712.06:006:01
2812.05:596:01
2912.05:596:00
3012.05:586:00

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 6.12 kWh/m².

For context, solar energy here swings from a low near 4.18 kWh/m² to a high of 6.15 kWh/m² in October across the year — September's 6.12 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
16.0Bright
26.0Bright
36.0Intense
46.0Intense
56.0Intense
66.0Intense
76.0Intense
86.0Intense
96.1Intense
106.1Intense
116.1Intense
126.1Intense
136.1Intense
146.1Intense
156.1Intense
166.1Intense
176.1Intense
186.1Intense
196.2Intense
206.2Intense
216.2Intense
226.2Intense
236.2Intense
246.2Intense
256.2Intense
266.2Intense
276.2Intense
286.2Intense
296.2Intense
306.2Intense
Planning a trip in September

Hazard calendar for Ulianópolis

In seasonPeak

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

Ulianópolis's monsoon runs January–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 Ulianópolis?

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

3.2
Sightseeing
5th-best month of the year
6.7
Beach & pool
4th-best month of the year

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

What to pack for Ulianópolis in September

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

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

light clothessun protection

UV index in Ulianópolis 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 Ulianópolis peaks around March 15 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near July 17 at about 10 (extreme).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeMar 15UV 15Jul 17UV 10
UV index (midday)Level
Jan13Extreme
Feb14Extreme
Mar15Extreme
Apr14Extreme
May11Extreme
Jun10Extreme
Jul10Extreme
Aug10Extreme
Sep12Extreme
Oct12Extreme
Nov11Extreme
Dec10Extreme

Air quality in Ulianópolis 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 Ulianópolis is worst in November — around 33 µg/m³ PM2.5 (moderate), about 3.7× the cleanest month (June, 9 µg/m³).

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

010203040JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateNov 2033 µg/m³Jun 139 µg/m³
PM2.5 (µg/m³)Level
Jan16Moderate
Feb16Moderate
Mar15Moderate
Apr12Moderate
May10Good
Jun9Good
Jul11Good
Aug13Moderate
Sep16Moderate
Oct21Moderate
Nov33Moderate
Dec30Moderate
Location & terrain

Where is Ulianópolis?

Ulianópolis sits at 3.7°S, 47.5°W, 119 m above sea level, in Brazil. The nearest listed city is Dom Eliseu, 60 km away.

Topography around Ulianópolis

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

Within 3 km, the terrain around Ulianópolis has only modest variations in elevation — a maximum elevation change of 47 m around an average of 113 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 152 m; within 80 km, significant variations in elevation — a maximum elevation change of 304 m.

The land around Ulianópolis is covered by grassland (62%) and trees (26%) within 3 km, grassland (51%) and trees (48%) within 16 km, and trees (65%) and grassland (33%) within 80 km.

3 km
47 m
16 km
152 m
80 km
304 m
treesgrasslandcroplandartificial surfacesbare terrain
September weather nearby: Dom Eliseu 60 km · Itinga do Maranhão 79 km · Paragominas 84 km · Bom Jesus das Selvas 109 km · Rondon do Pará 131 km · Ipixuna do Pará 132 km · Buriticupu 132 km · Açailândia 134 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 Ulianópolis (-3.7419°, -47.4947°, elevation 119 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).