Custoias weather in December

In December, Custoias sees average daytime highs of 10°C and overnight lows near 4°C, with 68 mm of precipitation across 8.3 wet days and about 9.1 hours of daylight. It is the 11th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 10°C through the month. The sky is clear or mostly clear about 23% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 h 18 min at the start of December to 9 h 06 min by month's end. Set against the rest of the year, December is Custoias's 12th-clearest and 10th-windiest month. For the whole year in context, see Custoias's year-round climate.

Daytime high
10°
11th warmest
Overnight low
3rd coldest
Precipitation
68 mm
8.3 wet days
Daylight
9 h 06 min
7:54 AM – 4:57 PM
Cloud cover
66%
12th clearest
Wind
8 km/h
10th windiest
Solar energy
1.57 kWh/m²
Travel score
2.5
out of 10

Custoias is human settlement in Portugal.

Air quality
Good
PM10 27.6 µg/m³ · 2010

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

Temperature in December

Average highAverage lowShaded bands: 10–90% of days

Day-to-day highs hold fairly steady near 10°C through the month.

A typical December day in Custoias reaches about 10°C in the afternoon and slips back to 4°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 7°C and 14°C. Set against its neighbours, December runs about 3°C cooler than November and on par with January.

-5°10°15°151015202531
Avg high (°C)Avg low (°C)
1114
2114
3114
4114
5114
6114
7114
8114
9114
10114
11104
12104
13104
14104
15104
16103
17103
18103
19103
20103
21103
22103
23103
24103
25103
26103
27103
28103
29103
30103
31103

Custoias weather by month

How December compares with the rest of the year at a glance. December is the 11th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan10° / 628.79.42.3
Feb12° / 436.610.43.5
Mar15° / 497.911.74.9
Apr17° / 549.813.15.6
May21° / 10°499.214.36.7
Jun26° / 13°204.814.97.8
Jul29° / 15°122.614.77.1
Aug29° / 15°133.413.67.1
Sep25° / 13°344.612.37.9
Oct19° / 10°839.310.96.3
Nov13° / 699.29.73.9
Dec10° / 688.39.12.5

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 23% of the time in December, the cloudiest month of the year.

Beyond those clear spells, partly cloudy skies cover about 15% of December, with mostly cloudy or overcast conditions the remaining 62%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13961
23862
33763
43763
53763
63763
73763
83862
93862
103862
113961
123961
133961
143961
153961
164060
174060
184060
194060
204060
214060
224060
234060
243862
253862
263763
273664
283664
293763
303664
313664

Chance of precipitation in December

Any precipitationSnow

Custoias gets around 68 mm of rain and snow over 8.3 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable precipitation averages around 27% and peaks near 31% on the wettest days, and about 0 day brings snow.

0%10%20%30%40%151015202531
Rain chance (%)Snow chance (%)
1280
2280
3270
4270
5260
6260
7260
8250
9250
10250
11250
12250
13251
14261
15261
16261
17261
18261
19271
20271
21281
22281
23281
24291
25291
26302
27302
28302
29302
30312
31312

Humidity in December

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, December lands in the dry band about 100% of days. It rarely turns muggy — the humid and sticky bands barely register.

0%25%50%75%100%151015202531
Dry (%)
1100
2100
3100
4100
5100
6100
7100
8100
9100
10100
11100
12100
13100
14100
15100
16100
17100
18100
19100
20100
21100
22100
23100
24100
25100
26100
27100
28100
29100
30100
31100

Wind in December

Winds average 8 km/h in December.

Across December, 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.

051015151015202531
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
318calm

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 h 18 min at the start of December to 9 h 06 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 12 minutes over December. Sunrise moves from 7:41 AM to 8:00 AM, and sunset from 4:57 PM to 5:05 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.37:414:57
29.27:424:57
39.27:434:56
49.27:444:56
59.27:454:56
69.27:464:56
79.27:474:56
89.17:484:56
99.17:494:56
109.17:494:56
119.17:504:56
129.17:514:56
139.17:524:56
149.17:524:57
159.17:534:57
169.17:544:57
179.07:544:57
189.07:554:58
199.07:564:58
209.07:564:58
219.07:574:59
229.07:574:59
239.07:585:00
249.07:585:00
259.07:585:01
269.07:595:01
279.07:595:02
289.17:595:03
299.18:005:03
309.18:005:04
319.18:005:05

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.57 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.57 kWh/m² to a high of 7.49 kWh/m² in July across the year — December's 1.57 kWh/m² sits near the bottom.

00.511.522.5151015202531
Solar energy (kWh/m²)Level
11.7Dim
21.7Dim
31.7Dim
41.7Dim
51.6Dim
61.6Dim
71.6Dim
81.6Dim
91.6Dim
101.6Dim
111.6Dim
121.6Dim
131.6Dim
141.6Dim
151.6Dim
161.6Dim
171.6Dim
181.6Dim
191.6Dim
201.6Dim
211.6Dim
221.6Dim
231.6Dim
241.6Dim
251.6Dim
261.6Dim
271.6Dim
281.6Dim
291.6Dim
301.6Dim
311.6Dim
Planning a trip in December

Is December a good time to visit Custoias?

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

2.5
Sightseeing
11th-best month of the year
0.0
Beach & pool
11th-best month of the year

December is a weaker month for outdoor sightseeing in Custoias.

What to pack for Custoias in December

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

In December, Custoias sees daytime highs around 10°C and nights near 4°C. Pack a warm layer. Worth having: rain gear. About 8 days see rain.

a warm layerrain gear

UV index in Custoias in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 2. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Custoias peaks around July 12 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 12UV 9Dec 20UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar5High
Apr6High
May7High
Jun9Very high
Jul9Very high
Aug9Very high
Sep6High
Oct5Moderate
Nov2Moderate
Dec2Low

Air quality in Custoias in December

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where December falls, not just the annual average.

Air quality in Custoias is worst in August — around 22 µg/m³ PM2.5 (moderate), about 3.2× the cleanest month (November, 7 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodModerateGoodAug 1922 µg/m³Nov 237 µg/m³
PM2.5 (µg/m³)Level
Jan10Good
Feb10Good
Mar13Moderate
Apr11Good
May8Good
Jun9Good
Jul12Good
Aug22Moderate
Sep18Moderate
Oct13Moderate
Nov7Good
Dec7Good
Location & terrain

Where is Custoias?

Custoias sits at 41.1°N, 7.3°W, 569 m above sea level, in Portugal. The nearest listed city is Vila Nova de Foz Côa, 15 km away.

Topography around Custoias

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

Within 3 km, the terrain around Custoias has large variations in elevation — a maximum elevation change of 671 m around an average of 479 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 921 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,573 m.

The land around Custoias is covered by shrubs (40%), grassland (30%) and trees (29%) within 3 km, grassland (44%), trees (26%) and shrubs (23%) within 16 km, and grassland (58%) and trees (30%) within 80 km.

3 km
671 m
16 km
921 m
80 km
1,573 m
treesshrubsgrasslandcroplandartificial surfaceswater
December weather nearby: Vila Nova de Foz Côa 15 km · Vila Real 41 km · Baião 60 km · Sequeira 62 km · Guarda 63 km · Viseu 70 km · Chaves 72 km · Cabeceiras de Basto 72 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 Custoias (41.1053°, -7.321°, elevation 569 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).