Porto Acre weather in September

In September, Porto Acre sees average daytime highs of 33°C and overnight lows near 22°C, with 90 mm of rain across 13.4 wet days and about 11.9 hours of daylight. It is the 1st-warmest and 9th-wettest month of the year here.

Day-to-day highs hold fairly steady near 33°C through the month. The sky is clear or mostly clear about 27% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 11 h 48 min at the start of September to 12 h 06 min by month's end. Set against the rest of the year, September is Porto Acre's 4th-clearest and 2nd-windiest month. For the whole year in context, see Porto Acre's year-round climate.

Daytime high
33°
1st warmest
Overnight low
22°
5th coldest
Rainfall
90 mm
13.4 wet days
Daylight
11 h 54 min
5:26 AM – 5:23 PM
Cloud cover
59%
4th clearest
Wind
6 km/h
2nd windiest
Solar energy
5.53 kWh/m²
Travel score
3.1
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 33°C through the month.

A typical September day in Porto Acre reaches about 33°C in the afternoon and slips back to 22°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 29°C and 36°C. Set against its neighbours, September runs on par with August and on par with October.

15°20°25°30°35°40°151015202530
Avg high (°C)Avg low (°C)
13322
23322
33322
43322
53322
63322
73322
83322
93322
103322
113322
123322
133322
143322
153322
163322
173322
183322
193322
203322
213322
223322
233322
243322
253322
263322
273322
283322
293323
303323

How September really feels in Porto Acre

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.

Porto Acre 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
Jan30° / 23°26427.612.52.7
Feb30° / 23°26925.412.32.7
Mar30° / 23°2822812.12.7
Apr30° / 22°18924.811.83.0
May30° / 22°10217.511.64.1
Jun30° / 21°418.611.55.0
Jul31° / 20°26511.55.0
Aug33° / 21°477.511.73.9
Sep33° / 22°9013.411.93.1
Oct32° / 23°15220.712.22.8
Nov31° / 23°21323.812.42.7
Dec31° / 23°26627.312.52.7

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 27% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 24% of September, with mostly cloudy or overcast conditions the remaining 50%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
16337
26337
36139
46139
55941
65941
75743
85743
95644
105545
115446
125347
135149
145149
155050
164951
174951
184753
194654
204654
214555
224456
234555
244456
254357
264258
274258
284060
293961
303961

Chance of precipitation in September

Any precipitation

Porto Acre gets around 90 mm of rain over 13.4 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 45% and peaks near 55% on the wettest days. The odds climb toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
135
235
336
436
537
638
738
839
940
1040
1141
1242
1342
1443
1544
1645
1746
1847
1948
2049
2149
2250
2351
2451
2552
2653
2753
2854
2955
3055

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 77% of days. Sticky, muggy-or-worse air turns up on roughly 94% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
123716702
223715712
322715722
422715731
512714742
612614752
712614752
812614752
912514762
1012513772
1112513763
1212413773
1312412774
1402412784
1502412784
1602311795
1702311795
1802310796
1902310796
2002310787
210239797
220239788
230229798
240228808
250228808
260228799
270128809
280117829
290117829
3001178110

Wind in September

Winds average 6 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 6 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
246calm
256calm
266calm
276calm
286calm
296calm
306calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 48 min at the start of September to 12 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 18 minutes over September. Sunrise moves from 5:35 AM to 5:17 AM, and sunset from 5:24 PM to 5:22 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.85:355:24
211.85:355:24
311.85:345:24
411.85:345:24
511.85:335:24
611.95:325:24
711.95:325:24
811.95:315:24
911.95:315:24
1011.95:305:23
1111.95:295:23
1211.95:295:23
1311.95:285:23
1411.95:275:23
1511.95:275:23
1611.95:265:23
1712.05:255:23
1812.05:255:23
1912.05:245:23
2012.05:235:22
2112.05:235:22
2212.05:225:22
2312.05:225:22
2412.05:215:22
2512.05:205:22
2612.05:205:22
2712.05:195:22
2812.15:185:22
2912.15:185:22
3012.15:175:22

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.53 kWh/m² — the sunniest month for solar.

For context, solar energy here swings from a low near 4.21 kWh/m² to a high of 5.53 kWh/m² in September across the year — September's 5.53 kWh/m² sits near the top of that range.

0246151015202530
Solar energy (kWh/m²)Level
15.5Bright
25.5Bright
35.5Bright
45.5Bright
55.5Bright
65.5Bright
75.5Bright
85.5Bright
95.5Bright
105.5Bright
115.5Bright
125.5Bright
135.5Bright
145.5Bright
155.5Bright
165.5Bright
175.5Bright
185.5Bright
195.6Bright
205.6Bright
215.6Bright
225.6Bright
235.6Bright
245.6Bright
255.6Bright
265.6Bright
275.6Bright
285.6Bright
295.6Bright
305.6Bright
Planning a trip in September

Hazard calendar for Porto Acre

In seasonPeak

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

Porto Acre's rainy season runs October–April, when most of the year's rain falls.

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

Is September a good time to visit Porto Acre?

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

3.1
Sightseeing
5th-best month of the year
5.6
Beach & pool
4th-best month of the year

September is a weaker month for outdoor sightseeing in Porto Acre.

What to pack for Porto Acre in September

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

In September, Porto Acre sees daytime highs around 33°C and nights near 22°C. Pack light clothes. Worth having: rain gear and sun protection. About 13 days see rain.

light clothesrain gearsun protection

UV index in Porto Acre in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Porto Acre peaks around January 20 at about 15 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near September 10 at about 5 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighExtremeJan 20UV 15Sep 10UV 5
UV index (midday)Level
Jan15Extreme
Feb15Extreme
Mar15Extreme
Apr13Extreme
May11Extreme
Jun9Very high
Jul8Very high
Aug6High
Sep5Moderate
Oct12Extreme
Nov13Extreme
Dec13Extreme

Air quality in Porto Acre 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 Porto Acre is worst in September — around 100 µg/m³ PM2.5 (unhealthy), about 12.4× the cleanest month (June, 8 µg/m³).

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

0306090120JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodModerateUnhealthyModerateGoodSep 1394 µg/m³Jun 98 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar13Moderate
Apr10Good
May8Good
Jun8Good
Jul14Moderate
Aug65Unhealthy
Sep100Unhealthy
Oct27Moderate
Nov13Moderate
Dec11Good
Location & terrain

Where is Porto Acre?

Porto Acre sits at 9.6°S, 67.5°W, 121 m above sea level, in Brazil. The nearest listed city is Rio Branco, 53 km away.

Topography around Porto Acre

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

Within 3 km, the terrain around Porto Acre has only modest variations in elevation — a maximum elevation change of 70 m around an average of 140 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 105 m; within 80 km, only modest variations in elevation — a maximum elevation change of 145 m.

The land around Porto Acre is covered by trees (74%) and grassland (23%) within 3 km, trees (68%) and grassland (31%) within 16 km, and trees (65%) and grassland (35%) within 80 km.

3 km
70 m
16 km
105 m
80 km
145 m
treesgrasslandartificial surfaceswater
September weather nearby: Rio Branco 53 km · Senador Guiomard 66 km · Plácido de Castro 91 km · Boca do Acre 94 km · Sena Madureira 138 km · Xapuri 159 km · Brasiléia 207 km · Epitaciolândia 208 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 Porto Acre (-9.5883°, -67.5325°, elevation 121 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).