São Mateus weather in September

In September, São Mateus sees average daytime highs of 25°C and overnight lows near 22°C, with 54 mm of rain across 10.8 wet days and about 11.9 hours of daylight. It is the 9th-warmest and 10th-wettest month of the year here.

Day-to-day highs hold fairly steady near 25°C through the month. The sky is clear or mostly clear about 47% of the time in September, and the air most often feels muggy.

Daylight stretches from about 11 h 36 min at the start of September to 12 h 12 min by month's end. Set against the rest of the year, September is São Mateus's 4th-clearest and 3rd-windiest month. For the whole year in context, see São Mateus's year-round climate.

Daytime high
25°
9th warmest
Overnight low
22°
4th coldest
Rainfall
54 mm
10.8 wet days
Daylight
11 h 54 min
6:37 AM – 6:31 PM
Cloud cover
48%
4th clearest
Wind
19 km/h
3rd windiest
Solar energy
5.38 kWh/m²
Travel score
6.9
out of 10

São Mateus 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 25°C through the month.

A typical September day in São Mateus reaches about 25°C in the afternoon and slips back to 22°C overnight — a 3°C spread between the day's warmth and the night's chill. On most days the high lands between 23°C and 27°C. Set against its neighbours, September runs on par with August and about 1°C cooler than October.

15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12521
22521
32521
42521
52521
62521
72521
82521
92521
102521
112521
122522
132522
142522
152522
162522
172522
182522
192522
202522
212522
222522
232522
242522
252522
262522
272522
282522
292522
302522

São Mateus weather by month

How September compares with the rest of the year at a glance. September is the 9th-warmest and 10th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan28° / 24°10613.4135.9
Feb28° / 24°7613.912.65.4
Mar28° / 24°13618.212.15.2
Apr27° / 24°10816.911.65.6
May26° / 22°7013.211.16.4
Jun25° / 21°5211.810.96.8
Jul24° / 21°5713.2116.8
Aug24° / 21°4811.211.47.1
Sep25° / 22°5410.811.96.9
Oct26° / 23°9613.412.46.2
Nov26° / 23°18317.612.95.3
Dec27° / 24°14715.513.15.5

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 47% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 21% of September, with mostly cloudy or overcast conditions the remaining 32%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17624
27624
37624
47624
57624
67624
77624
87525
97525
107426
117327
127228
137129
147129
157030
166931
176832
186634
196535
206436
216238
226238
236040
246040
255842
265842
275743
285644
295644
305644

Chance of precipitation in September

Any precipitation

São Mateus gets around 54 mm of rain over 10.8 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 36% and peaks near 38% on the wettest days.

0%10%20%30%40%50%151015202530
Rain chance (%)
133
233
333
434
534
635
735
836
936
1037
1137
1237
1338
1438
1538
1638
1738
1838
1937
2037
2137
2237
2336
2436
2536
2635
2735
2836
2936
3036

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 62% of days. Sticky, muggy-or-worse air turns up on roughly 74% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
11823626
21823617
31823617
41823617
51823608
61823608
70823618
80822628
90822619
100821629
110721639
120721639
1307206310
1406206410
1506196510
1606196411
1705196511
1805186512
1905186512
2005186512
2105186413
2205176414
2305176315
2405176216
2505176117
2605176018
2705175919
2805175820
2905175721
3005175622

Wind in September

Winds average 19 km/h in September.

Across September, daily wind ranges from about 18 km/h on the calmest days to 20 km/h at its breeziest. It stays fairly steady from day to day.

0510152025151015202530
Wind speed (km/h)Feels
118light breeze
218light breeze
318light breeze
418light breeze
518light breeze
618light breeze
718light breeze
818light breeze
918light breeze
1019light breeze
1119light breeze
1219light breeze
1319light breeze
1419light breeze
1519light breeze
1619light breeze
1719light breeze
1819light breeze
1919light breeze
2019light breeze
2119light breeze
2219light breeze
2319light breeze
2419light breeze
2520light breeze
2620light breeze
2720light breeze
2820light breeze
2920light breeze
3020light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 11 h 36 min at the start of September to 12 h 12 min by month's end. The lit band spans sunrise to sunset each day.

Days grow by about 36 minutes over September. Sunrise moves from 6:50 AM to 6:24 AM, and sunset from 6:28 PM to 6:33 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
111.66:506:28
211.66:496:28
311.76:496:28
411.76:486:29
511.76:476:29
611.76:466:29
711.76:456:29
811.86:446:29
911.86:436:29
1011.86:426:30
1111.86:416:30
1211.86:416:30
1311.86:406:30
1411.96:396:30
1511.96:386:30
1611.96:376:31
1711.96:366:31
1811.96:356:31
1911.96:346:31
2012.06:336:31
2112.06:326:31
2212.06:316:32
2312.06:306:32
2412.06:306:32
2512.16:296:32
2612.16:286:32
2712.16:276:33
2812.16:266:33
2912.16:256:33
3012.26:246:33

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 5.38 kWh/m².

For context, solar energy here swings from a low near 3.83 kWh/m² to a high of 6.76 kWh/m² in January across the year — September's 5.38 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.1Bright
25.2Bright
35.2Bright
45.2Bright
55.2Bright
65.2Bright
75.3Bright
85.3Bright
95.3Bright
105.3Bright
115.3Bright
125.3Bright
135.3Bright
145.3Bright
155.4Bright
165.4Bright
175.4Bright
185.4Bright
195.4Bright
205.4Bright
215.4Bright
225.5Bright
235.5Bright
245.5Bright
255.5Bright
265.5Bright
275.5Bright
285.6Bright
295.6Bright
305.6Bright
Planning a trip in September

Is September a good time to visit São Mateus?

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

6.9
Sightseeing
2nd-best month of the year
6.2
Beach & pool
2nd-best month of the year

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

What to pack for São Mateus in September

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

In September, São Mateus sees daytime highs around 25°C and nights near 22°C. Worth packing: light clothes, rain gear and sun protection. About 11 days see rain.

light clothesrain gearsun protection

Sea temperature near São Mateus in September

The nearest coast averages about 25°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 27 km away) is warmest in March at about 28°C and coldest in August near 24°C.

The water stays above 20°C all year — warm enough for a swim any month.

22°24°26°28°JanFebMarAprMayJunJulAugSepOctNovDecrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan27Warm
Feb27Warm
Mar28Warm
Apr27Warm
May26Warm
Jun25Warm
Jul24Warm
Aug24Warm
Sep25Warm
Oct25Warm
Nov26Warm
Dec26Warm

UV index in São Mateus in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (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 Mateus peaks around February 13 at about 14 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near June 20 at about 7 (high).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecExtremeVery highHighVery highExtremeFeb 13UV 14Jun 20UV 7
UV index (midday)Level
Jan14Extreme
Feb15Extreme
Mar13Extreme
Apr10Extreme
May8Very high
Jun7High
Jul7High
Aug9Very high
Sep10Extreme
Oct12Extreme
Nov14Extreme
Dec13Extreme
Location & terrain

Where is São Mateus?

São Mateus sits at 18.7°S, 39.9°W, 38 m above sea level, in Brazil. The nearest listed city is Conceição da Barra, 19 km away.

Topography around São Mateus

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

Within 3 km, the terrain around São Mateus has only modest variations in elevation — a maximum elevation change of 51 m around an average of 22 m above sea level; within 16 km, only modest variations in elevation — a maximum elevation change of 95 m; within 80 km, large variations in elevation — a maximum elevation change of 744 m.

The land around São Mateus is covered by trees (34%), artificial surfaces (26%) and grassland (21%) within 3 km, trees (55%) and grassland (26%) within 16 km, and grassland (37%), trees (33%) and water (27%) within 80 km.

3 km
51 m
16 km
95 m
80 km
744 m
treesgrasslandcroplandartificial surfacesbare terrainwaterwetland
September weather nearby: Conceição da Barra 19 km · Jaguaré 31 km · Pinheiros 54 km · Nova Venécia 57 km · Sooretama 59 km · Mucuri 78 km · Linhares 78 km · Rio Bananal 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 Mateus (-18.7201°, -39.8589°, elevation 38 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. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).