Viseu weather in September

In September, Viseu sees average daytime highs of 24°C and overnight lows near 13°C, with 66 mm of rain across 7.1 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 9th-wettest month of the year here.

Highs ease over the month, from about 25°C in the first days to 22°C by the end. The sky is clear or mostly clear about 52% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Viseu's 3rd-clearest and 12th-windiest month. For the whole year in context, see Viseu's year-round climate.

Daytime high
24°
3rd warmest
Overnight low
13°
10th coldest
Rainfall
66 mm
7.1 wet days
Daylight
12 h 18 min
6:18 AM – 6:34 PM
Cloud cover
41%
3rd clearest
Wind
8 km/h
12th windiest
Solar energy
4.86 kWh/m²
Travel score
7.6
out of 10

Viseu is city seat of Viseu municipality.

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

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 25°C in the first days to 22°C by the end.

A typical September day in Viseu reaches about 24°C in the afternoon and slips back to 13°C overnight — a 11°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 29°C. Set against its neighbours, September runs about 3°C cooler than August and about 5°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12614
22614
32514
42514
52514
62514
72514
82514
92514
102514
112414
122414
132413
142413
152413
162413
172313
182313
192313
202313
212313
222313
232212
242212
252212
262212
272212
282212
292212
302112

Viseu weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 9th-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan11° / 15211.60.59.42.5
Feb12° / 1029.30.310.43.3
Mar15° / 11510.6011.74.5
Apr17° / 11812.8013.14.9
May20° / 10°9811.6014.26.1
Jun23° / 13°406.2014.97.7
Jul27° / 15°193.7014.68.2
Aug27° / 15°264.6013.68.0
Sep24° / 13°667.1012.37.6
Oct19° / 10°16812.2010.95.7
Nov14° / 15012.70.19.73.7
Dec11° / 16011.60.19.12.7

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 15% of September, with mostly cloudy or overcast conditions the remaining 33%. Skies tend to cloud over as the month goes on.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
17822
27822
37822
47624
57624
67525
77426
87327
97228
107030
117030
126931
136832
146733
156634
166535
176535
186436
196337
206337
216238
226238
236139
246139
256040
266040
275941
285941
295941
305941

Chance of precipitation in September

Any precipitation

Viseu gets around 66 mm of rain over 7.1 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 24% and peaks near 28% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%151015202530
Rain chance (%)
118
218
318
418
518
618
719
819
920
1021
1122
1223
1323
1424
1525
1625
1726
1826
1927
2027
2127
2228
2328
2428
2528
2628
2728
2827
2927
3028

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 63% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)
148457
249456
350446
452435
553425
654415
756404
857394
958384
1059374
1160364
1261354
1362344
1463343
1564333
1665323
1766313
1867303
1968302
2069292
2169292
2270282
2370282
2471272
2572262
2672262
2773252
2872253
2973243
3073243

Wind in September

Winds average 8 km/h in September, the calmest month.

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

051015151015202530
Wind speed (km/h)Feels
18calm
28calm
38calm
48calm
58calm
68calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 6:03 AM to 6:32 AM, and sunset from 7:00 PM to 6:10 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.96:037:00
212.96:046:58
312.96:056:56
412.86:066:55
512.86:076:53
612.76:086:51
712.76:096:50
812.66:106:48
912.66:116:46
1012.56:126:44
1112.56:136:43
1212.46:146:41
1312.46:156:39
1412.46:166:37
1512.36:176:36
1612.36:186:34
1712.26:196:32
1812.26:206:30
1912.16:216:29
2012.16:226:27
2112.06:236:25
2212.06:246:23
2311.96:256:22
2411.96:266:20
2511.86:276:18
2611.86:286:16
2711.86:296:15
2811.76:306:13
2911.76:316:11
3011.66:326:10

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.86 kWh/m².

For context, solar energy here swings from a low near 1.66 kWh/m² to a high of 7.25 kWh/m² in July across the year — September's 4.86 kWh/m² falls in the middle.

0246151015202530
Solar energy (kWh/m²)Level
15.7Bright
25.7Bright
35.6Bright
45.5Bright
55.5Bright
65.4Bright
75.4Bright
85.3Bright
95.2Bright
105.2Bright
115.1Bright
125.0Bright
135.0Bright
144.9Bright
154.9Bright
164.8Bright
174.7Bright
184.7Bright
194.6Bright
204.6Bright
214.5Bright
224.5Bright
234.4Bright
244.4Bright
254.3Bright
264.3Bright
274.2Bright
284.2Bright
294.1Bright
304.1Bright
Planning a trip in September

Hazard calendar for Viseu

In seasonPeak

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

Viseu's rainy season runs October–May, 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 Viseu?

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

7.6
Sightseeing
4th-best month of the year
6.1
Beach & pool
4th-best month of the year

September is one of the better times to visit Viseu for general sightseeing. The water and warmth also suit a beach or pool day.

What to pack for Viseu in September

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

In September, Viseu sees daytime highs around 24°C and nights near 13°C. Worth packing: light clothes and sun protection. About 7 days see rain.

light clothessun protection

UV index in Viseu in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 6 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Viseu peaks around July 13 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 20 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highHighModerateLowJul 13UV 9Dec 20UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5High
Apr7High
May7High
Jun9Very high
Jul9Very high
Aug9Very high
Sep6High
Oct5Moderate
Nov2Moderate
Dec2Low

Air quality in Viseu 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 Viseu is worst in October — around 29 µg/m³ PM2.5 (moderate), about 3.9× the cleanest month (November, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateModerateGoodOct 1228 µg/m³Nov 237 µg/m³
PM2.5 (µg/m³)Level
Jan9Good
Feb10Good
Mar13Moderate
Apr11Good
May8Good
Jun21Moderate
Jul9Good
Aug24Moderate
Sep23Moderate
Oct29Moderate
Nov7Good
Dec7Good
Location & terrain

Where is Viseu?

Viseu sits at 40.7°N, 7.9°W, 469 m above sea level, in Portugal. The nearest listed city is Arouca, 41 km away.

Topography around Viseu

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

Within 3 km, the terrain around Viseu has only modest variations in elevation — a maximum elevation change of 165 m around an average of 466 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 814 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,993 m.

The land around Viseu is covered by trees (45%) and artificial surfaces (35%) within 3 km, trees (56%) and grassland (36%) within 16 km, and trees (48%) and grassland (41%) within 80 km.

3 km
165 m
16 km
814 m
80 km
1,993 m
treesshrubsgrasslandcroplandartificial surfaceswater
September weather nearby: Arouca 41 km · Covilhã 54 km · São João da Madeira 56 km · Guarda 56 km · Baião 57 km · Sequeira 59 km · Feira 61 km · Vilar 61 km

Portugal travel facts

Travel advisory
Level 1
Exercise Normal Precautions
Power plugs
Type C / E / F
230 V · 50 Hz
Prices
≈ 60% of US
price level, 2025
GDP per capita
$32,082
2025
Happiness
6.0 / 10
World Happiness, 2025
Safe drinking water
95%
of population, 2024
Homicide rate
0.7
per 100k, 2022
Road deaths
8.2
per 100k/yr, 2019
Income group
High
World Bank
English
Very high
EF EPI 612
Religion
Catholic 68%not applicable 13%no religion 12%no response 2%

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 Viseu (40.6617°, -7.909°, elevation 469 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).