Guaíba weather in September

In September, Guaíba sees average daytime highs of 22°C and overnight lows near 13°C, with 146 mm of rain across 11.1 wet days and about 11.8 hours of daylight. It is the 8th-warmest and 2nd-wettest month of the year here.

Day-to-day highs hold fairly steady near 22°C through the month. The sky is clear or mostly clear about 29% of the time in September, and the air most often feels dry.

Daylight stretches from about 11 h 24 min at the start of September to 12 h 18 min by month's end. Set against the rest of the year, September is Guaíba's 10th-clearest and 2nd-windiest month. For the whole year in context, see Guaíba's year-round climate.

Daytime high
22°
8th warmest
Overnight low
13°
4th coldest
Rainfall
146 mm
11.1 wet days
Daylight
11 h 48 min
7:25 AM – 7:14 PM
Cloud cover
63%
10th clearest
Wind
12 km/h
2nd windiest
Solar energy
4.06 kWh/m²
Travel score
6.4
out of 10

Guaíba 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 22°C through the month.

A typical September day in Guaíba reaches about 22°C in the afternoon and slips back to 13°C overnight — a 9°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 28°C. Set against its neighbours, September runs about 1°C warmer than August and about 2°C cooler than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12213
22213
32213
42213
52213
62213
72213
82213
92213
102213
112213
122213
132213
142213
152213
162213
172213
182213
192213
202213
212213
222214
232214
242214
252214
262214
272314
282314
292314
302314

How September really feels in Guaíba

Once humidity and wind are folded in, September averages 0 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
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Guaíba weather by month

How September compares with the rest of the year at a glance. September is the 8th-warmest and 2nd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan30° / 21°13714.113.74.6
Feb30° / 21°12613.313.14.6
Mar28° / 20°11211.912.25.7
Apr26° / 17°1069.211.36.8
May22° / 13°1079.210.56.7
Jun20° / 11°1139.210.16.2
Jul19° / 10°1401010.36.1
Aug21° / 11°12010.210.96.5
Sep22° / 13°14611.111.86.4
Oct24° / 16°17012.512.76.4
Nov27° / 17°12310.813.56.4
Dec29° / 20°12511.713.95.2

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 29% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 12% of September, with mostly cloudy or overcast conditions the remaining 59%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14654
24654
34456
44456
54258
64258
74060
84060
94060
103961
114060
123961
134060
143961
154060
164060
173961
184060
194159
204159
214258
224258
234159
244159
254060
264060
273961
283961
293763
303763

Chance of precipitation in September

Any precipitation

Guaíba gets around 146 mm of rain over 11.1 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 38% and peaks near 40% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
134
234
334
435
535
636
736
836
937
1037
1137
1238
1338
1438
1539
1639
1739
1839
1939
2039
2139
2238
2339
2439
2539
2639
2739
2840
2940
3040

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the dry band about 40% of days. Sticky, muggy-or-worse air turns up on roughly 6% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
14428253
24429253
34329253
44329253
54329254
64229254
74229254
84229254
94229264
104229264
114129264
124129264
134029274
144028275
154028275
164028275
174027275
184027276
194027276
204027276
214027266
224027267
233927267
243927277
253827278
263827278
273727279
283727279
2936272710
3036272710

Wind in September

Winds average 12 km/h in September.

Across September, daily wind ranges from about 11 km/h on the calmest days to 12 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
111calm
211calm
311calm
411calm
511calm
611calm
712calm
812calm
912calm
1012calm
1112calm
1212calm
1312calm
1412calm
1512calm
1612calm
1712calm
1812calm
1912calm
2012calm
2112calm
2212calm
2312calm
2412calm
2512calm
2612calm
2712calm
2812calm
2912calm
3012calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 24 min at the start of September to 12 h 18 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 54 minutes over September. Sunrise moves from 7:44 AM to 7:07 AM, and sunset from 7:06 PM to 7:22 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.47:447:06
211.47:437:06
311.47:427:07
411.57:407:08
511.57:397:08
611.57:387:09
711.57:377:09
811.67:357:10
911.67:347:10
1011.67:337:11
1111.77:327:11
1211.77:307:12
1311.77:297:13
1411.87:287:13
1511.87:267:14
1611.87:257:14
1711.97:247:15
1811.97:227:15
1911.97:217:16
2011.97:207:16
2112.07:187:17
2212.07:177:18
2312.07:167:18
2412.17:157:19
2512.17:137:19
2612.17:127:20
2712.27:117:21
2812.27:097:21
2912.27:087:22
3012.37:077:22

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.06 kWh/m².

For context, solar energy here swings from a low near 2.39 kWh/m² to a high of 6.58 kWh/m² in December across the year — September's 4.06 kWh/m² falls in the middle.

012345151015202530
Solar energy (kWh/m²)Level
13.7Moderate
23.8Moderate
33.8Moderate
43.8Moderate
53.8Moderate
63.8Moderate
73.8Moderate
83.9Moderate
93.9Moderate
103.9Moderate
113.9Moderate
124.0Moderate
134.0Moderate
144.0Bright
154.0Bright
164.1Bright
174.1Bright
184.1Bright
194.2Bright
204.2Bright
214.2Bright
224.2Bright
234.3Bright
244.3Bright
254.3Bright
264.3Bright
274.4Bright
284.4Bright
294.4Bright
304.4Bright
Planning a trip in September

Is September a good time to visit Guaíba?

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

6.4
Sightseeing
4th-best month of the year
4.5
Beach & pool
9th-best month of the year

September is a reasonable time to visit Guaíba for sightseeing.

What to pack for Guaíba in September

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

In September, Guaíba sees daytime highs around 22°C and nights near 13°C. Worth packing: light clothes and rain gear. About 11 days see rain.

light clothesrain gear

Sea temperature near Guaíba in September

The nearest coast averages about 17°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 35 km away) is warmest in February at about 26°C and coldest in July near 15°C.

It's comfortable for a long swim from Oct 23 to May 10 — about 6.6 months when the water holds above 20°C.

15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swimcomfortable to swim
Sea temperature (°C)Comfort
Jan26Warm
Feb26Warm
Mar25Warm
Apr23Refreshing
May19Cool
Jun17Cool
Jul15Cool
Aug16Cool
Sep17Cool
Oct20Cool
Nov22Refreshing
Dec24Warm

UV index in Guaíba in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Guaíba peaks around January 15 at about 13 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 19 at about 3 (moderate).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highModerateVery highExtremeJan 15UV 13Jun 19UV 3
UV index (midday)Level
Jan13Extreme
Feb12Extreme
Mar10Very high
Apr7Very high
May4Moderate
Jun3Moderate
Jul4Moderate
Aug5Moderate
Sep8Very high
Oct8Very high
Nov11Extreme
Dec12Extreme

Air quality in Guaíba 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 Guaíba is worst in August — around 27 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (December, 13 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateAug 1327 µg/m³Dec 2213 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb13Moderate
Mar15Moderate
Apr18Moderate
May21Moderate
Jun23Moderate
Jul25Moderate
Aug27Moderate
Sep23Moderate
Oct16Moderate
Nov15Moderate
Dec13Moderate
Location & terrain

Where is Guaíba?

Guaíba sits at 30.1°S, 51.3°W, 22 m above sea level, in Brazil. The nearest listed city is Porto Alegre, 13 km away.

Topography around Guaíba

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

Within 3 km, the terrain around Guaíba has only modest variations in elevation — a maximum elevation change of 126 m around an average of 15 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 293 m; within 80 km, large variations in elevation — a maximum elevation change of 800 m.

The land around Guaíba is covered by artificial surfaces (33%), water (24%) and trees (21%) within 3 km, water (25%), trees (23%) and cropland (22%) within 16 km, and trees (41%) and grassland (20%) within 80 km.

3 km
126 m
16 km
293 m
80 km
800 m
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Porto Alegre 13 km · Canoas 26 km · Alvorada 27 km · Eldorado do Sul 28 km · Cachoeirinha 29 km · Viamão 29 km · Nova Santa Rita 29 km · Esteio 31 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 Guaíba (-30.1139°, -51.325°, elevation 22 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. 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).