Castro-Urdiales weather in December

In December, Castro-Urdiales sees average daytime highs of 13°C and overnight lows near 10°C, with 117 mm of rain across 14.9 wet days and about 8.8 hours of daylight. It is the 10th-warmest and 3rd-wettest month of the year here.

Day-to-day highs hold fairly steady near 13°C through the month. The sky is clear or mostly clear about 18% of the time in December, and the air most often feels dry.

Daylight stretches from about 9 hours at the start of December to 8 h 48 min by month's end. Set against the rest of the year, December is Castro-Urdiales's 11th-clearest and 1st-windiest month. For the whole year in context, see Castro-Urdiales's year-round climate.

Daytime high
13°
10th warmest
Overnight low
10°
4th coldest
Rainfall
117 mm
14.9 wet days
Daylight
8 h 48 min
8:45 AM – 5:33 PM
Cloud cover
69%
11th clearest
Wind
18 km/h
1st windiest
Solar energy
1.4 kWh/m²
Travel score
3.3
out of 10

Castro-Urdiales is capital of Castro-Urdiales Municipality, Spain.

Air quality
Good
PM10 15.1 µg/m³ · 2019

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 13°C through the month.

A typical December day in Castro-Urdiales reaches about 13°C in the afternoon and slips back to 10°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 10°C and 17°C. Set against its neighbours, December runs about 2°C cooler than November and about 1°C warmer than January.

10°15°20°151015202531
Avg high (°C)Avg low (°C)
11410
21410
31410
41410
51410
61410
71310
81310
91310
101310
111310
121310
131310
141310
151310
161310
171310
18139
19139
20139
21139
22139
23139
24139
25139
26139
27139
28139
29139
30139
31139

Castro-Urdiales weather by month

How December compares with the rest of the year at a glance. December is the 10th-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysDaylight (hours)Travel score
Jan12° / 119159.22.9
Feb12° / 10313.510.22.9
Mar14° / 10°9813.211.63.7
Apr15° / 11°8913.813.24.0
May17° / 13°6912.714.55.1
Jun20° / 16°569.915.26.2
Jul22° / 18°469.114.96.9
Aug23° / 19°499.413.87.0
Sep21° / 17°6610.912.36.4
Oct19° / 15°10313.810.85.5
Nov15° / 12°15216.19.53.9
Dec13° / 10°11714.98.83.3

Cloud cover in December

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 18% of the time in December.

Beyond those clear spells, partly cloudy skies cover about 13% of December, with mostly cloudy or overcast conditions the remaining 69%.

0%25%50%75%100%151015202531
Clearer (%)Cloudier (%)
13070
23070
33070
43070
53070
63070
73169
83169
93169
103070
113070
123169
133169
143169
153169
163169
173169
183169
193268
203169
213169
223169
233169
243169
253169
263169
273169
283169
293169
303169
313268

Chance of precipitation in December

Any precipitation

Castro-Urdiales gets around 117 mm of rain over 14.9 wet days in December. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 48% and peaks near 54% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202531
Rain chance (%)
154
253
353
452
552
651
751
850
950
1049
1148
1248
1347
1447
1546
1646
1746
1846
1946
2046
2146
2246
2346
2446
2546
2645
2745
2846
2946
3046
3146

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 (%)Comfortable (%)
1991
2991
3991
4991
5991
6991
71000
81000
91000
101000
111000
121000
131000
141000
151000
161000
171000
181000
191000
201000
211000
221000
231000
241000
251000
261000
271000
281000
291000
301000
311000

Wind in December

Winds average 18 km/h in December, the windiest month of the year.

Across December, daily wind ranges from about 17 km/h on the calmest days to 18 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202531
Wind speed (km/h)Feels
117light breeze
217light breeze
318light breeze
418light breeze
518light breeze
617light breeze
717light breeze
817light breeze
917light breeze
1017light breeze
1117light breeze
1217light breeze
1317light breeze
1417light breeze
1517light breeze
1617light breeze
1717light breeze
1817light breeze
1917light breeze
2017light breeze
2117light breeze
2217light breeze
2317light breeze
2417light breeze
2517light breeze
2617light breeze
2717light breeze
2817light breeze
2917light breeze
3017light breeze
3117light breeze

Sunrise & sunset in December

DaylightNight

Daylight runs from about 9 hours at the start of December to 8 h 48 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 8:32 AM to 8:51 AM, and sunset from 5:33 PM to 5:41 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202531
Daylight (h)Sunrise (AM)Sunset (PM)
19.08:325:33
29.08:335:33
39.08:345:33
49.08:355:32
58.98:365:32
68.98:375:32
78.98:385:32
88.98:395:32
98.98:405:32
108.98:415:32
118.88:415:32
128.88:425:32
138.88:435:32
148.88:445:32
158.88:455:33
168.88:455:33
178.88:465:33
188.88:465:33
198.88:475:34
208.88:485:34
218.88:485:35
228.88:495:35
238.88:495:36
248.88:495:36
258.88:505:37
268.88:505:37
278.88:515:38
288.88:515:39
298.88:515:39
308.88:515:40
318.88:515:41

Solar energy in December

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in December, about 1.4 kWh/m² — the year's lowest.

For context, solar energy here swings from a low near 1.4 kWh/m² to a high of 6.12 kWh/m² in June across the year — December's 1.4 kWh/m² sits near the bottom.

00.511.52151015202531
Solar energy (kWh/m²)Level
11.5Dim
21.5Dim
31.5Dim
41.4Dim
51.4Dim
61.4Dim
71.4Dim
81.4Dim
91.4Dim
101.4Dim
111.4Dim
121.4Dim
131.4Dim
141.4Dim
151.4Dim
161.4Dim
171.4Dim
181.4Dim
191.4Dim
201.4Dim
211.4Dim
221.4Dim
231.4Dim
241.4Dim
251.4Dim
261.4Dim
271.4Dim
281.4Dim
291.4Dim
301.4Dim
311.4Dim
Planning a trip in December

Is December a good time to visit Castro-Urdiales?

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

3.3
Sightseeing
10th-best month of the year
0.0
Beach & pool
9th-best month of the year

December is a weaker month for outdoor sightseeing in Castro-Urdiales.

What to pack for Castro-Urdiales in December

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

In December, Castro-Urdiales sees daytime highs around 13°C and nights near 10°C. Pack rain gear. Worth having: a warm layer. About 15 days see rain.

rain geara warm layer

Sea temperature near Castro-Urdiales in December

The nearest coast averages about 14°C in December — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea offshore is warmest in August at about 22°C and coldest in February near 13°C.

It's comfortable for a long swim from Jul 11 to Sep 21 — about 2.4 months when the water holds above 20°C.

10°15°20°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingcomfortable to swim
Sea temperature (°C)Comfort
Jan13Bracing
Feb13Bracing
Mar13Bracing
Apr13Bracing
May15Cool
Jun18Cool
Jul21Refreshing
Aug22Refreshing
Sep20Refreshing
Oct18Cool
Nov16Cool
Dec14Bracing

UV index in Castro-Urdiales in December

LowModerateHighVery highExtreme

Clear-sky midday UV in December peaks around 1. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Castro-Urdiales peaks around July 15 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 1 (low).

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

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighModerateLowJul 15UV 9Dec 22UV 1
UV index (midday)Level
Jan2Low
Feb2Low
Mar5Moderate
Apr6High
May6High
Jun8Very high
Jul9Very high
Aug8Very high
Sep5High
Oct4Moderate
Nov2Low
Dec1Low
Location & terrain

Where is Castro-Urdiales?

Castro-Urdiales sits at 43.4°N, 3.2°W, 18 m above sea level, in Spain. The nearest listed city is Santurtzi, 16 km away.

Topography around Castro-Urdiales

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

Within 3 km, the terrain around Castro-Urdiales has significant variations in elevation — a maximum elevation change of 455 m around an average of 60 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 851 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,676 m.

The land around Castro-Urdiales is covered by water (46%) and trees (30%) within 3 km, water (50%) and trees (35%) within 16 km, and trees (37%), water (35%) and grassland (20%) within 80 km.

3 km
455 m
16 km
851 m
80 km
1,676 m
treesgrasslandcroplandartificial surfaceswater
December weather nearby: Santurtzi 16 km · Getxo 17 km · Algorta 17 km · Portugalete 18 km · Sestao 19 km · Leioa 20 km · Barakaldo 21 km · Erandio 22 km

Spain travel facts

Travel advisory
Level 2
Exercise Increased Caution
Power plugs
Type C / F
230 V · 50 Hz
Prices
≈ 65% of US
price level, 2025
GDP per capita
$38,627
2025
Happiness
6.5 / 10
World Happiness, 2025
Safe drinking water
99%
of population, 2024
Homicide rate
0.7
per 100k, 2023
Road deaths
3.9
per 100k/yr, 2019
Income group
High
World Bank
English
Moderate
EF EPI 540
Religion
Roman Catholic 58%atheist 16%agnostic 11%non-believer 11%

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 Castro-Urdiales (43.3828°, -3.2204°, elevation 18 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).