Castro-Urdiales weather in September

In September, Castro-Urdiales sees average daytime highs of 21°C and overnight lows near 17°C, with 66 mm of rain across 10.9 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 22°C in the first days to 20°C by the end. The sky is clear or mostly clear about 32% of the time in September, and the air most often feels comfortable.

Daylight stretches from about 13 hours at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Castro-Urdiales's 3rd-clearest and 9th-windiest month. For the whole year in context, see Castro-Urdiales's year-round climate.

Daytime high
21°
3rd warmest
Overnight low
17°
10th coldest
Rainfall
66 mm
10.9 wet days
Daylight
12 h 18 min
6:58 AM – 7:16 PM
Cloud cover
54%
3rd clearest
Wind
13 km/h
9th windiest
Solar energy
4.24 kWh/m²
Travel score
6.4
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 September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 22°C in the first days to 20°C by the end.

A typical September day in Castro-Urdiales reaches about 21°C in the afternoon and slips back to 17°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 18°C and 24°C. Set against its neighbours, September runs about 2°C cooler than August and about 2°C warmer than October.

10°15°20°25°151015202530
Avg high (°C)Avg low (°C)
12218
22218
32218
42218
52218
62218
72218
82218
92218
102118
112117
122117
132117
142117
152117
162117
172117
182117
192117
202117
212117
222117
232117
242017
252016
262016
272016
282016
292016
302016

Castro-Urdiales 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 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 September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 32% 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 47%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
15545
25545
35644
45743
55743
65743
75743
85743
95743
105644
115644
125644
135545
145446
155446
165347
175248
185149
195149
205149
215050
225050
235050
245050
254951
264951
274852
284753
294753
304753

Chance of precipitation in September

Any precipitation

Castro-Urdiales gets around 66 mm of rain over 10.9 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 37% and peaks near 43% on the wettest days. The odds climb toward the end of the month.

0%10%20%30%40%50%151015202530
Rain chance (%)
131
231
331
432
532
632
733
833
934
1035
1135
1236
1337
1437
1538
1638
1739
1839
1939
2039
2140
2240
2340
2440
2541
2641
2741
2842
2942
3043

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the comfortable band about 36% of days. Sticky, muggy-or-worse air turns up on roughly 9% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)
113323818
213323717
314333616
415343616
515343515
616353515
717353414
818353414
919353313
1019353313
1120353213
1221353212
1322353211
1423353211
1524353110
162535319
172635318
182735317
192835307
202836306
212936295
222937295
232937294
243038294
253038293
263138283
273138283
283238272
293338272
303438262

Wind in September

Winds average 13 km/h in September.

Across September, daily wind ranges from about 12 km/h on the calmest days to 14 km/h at its breeziest. It stays fairly steady from day to day.

05101520151015202530
Wind speed (km/h)Feels
112light breeze
212light breeze
312light breeze
412light breeze
512light breeze
613light breeze
713light breeze
813light breeze
913light breeze
1013light breeze
1113light breeze
1213light breeze
1313light breeze
1413light breeze
1513light breeze
1613light breeze
1713light breeze
1813light breeze
1913light breeze
2013light breeze
2114light breeze
2214light breeze
2314light breeze
2414light breeze
2514light breeze
2614light breeze
2714light breeze
2814light breeze
2914light breeze
3014light breeze

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 hours 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 84 minutes over September. Sunrise moves from 6:41 AM to 7:15 AM, and sunset from 7:44 PM to 6:50 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
113.06:417:44
213.06:427:42
312.96:447:40
412.96:457:38
512.86:467:37
612.86:477:35
712.76:487:33
812.76:497:31
912.66:507:29
1012.66:527:27
1112.56:537:25
1212.56:547:24
1312.46:557:22
1412.46:567:20
1512.36:577:18
1612.36:587:16
1712.27:007:14
1812.27:017:12
1912.17:027:10
2012.17:037:08
2112.07:047:06
2212.07:057:05
2311.97:077:03
2411.97:087:01
2511.87:096:59
2611.87:106:57
2711.77:116:55
2811.77:126:53
2911.67:146:51
3011.67:156:50

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.24 kWh/m².

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 — September's 4.24 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.8Bright
24.8Bright
34.8Bright
44.7Bright
54.7Bright
64.6Bright
74.6Bright
84.6Bright
94.5Bright
104.5Bright
114.4Bright
124.4Bright
134.3Bright
144.3Bright
154.2Bright
164.2Bright
174.1Bright
184.1Bright
194.0Bright
204.0Bright
214.0Moderate
223.9Moderate
233.9Moderate
243.8Moderate
253.8Moderate
263.7Moderate
273.7Moderate
283.6Moderate
293.6Moderate
303.5Moderate
Planning a trip in September

Is September a good time to visit Castro-Urdiales?

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

6.4
Sightseeing
3rd-best month of the year
3.9
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Castro-Urdiales for sightseeing.

What to pack for Castro-Urdiales in September

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

In September, Castro-Urdiales sees daytime highs around 21°C and nights near 17°C. Worth packing: rain gear. About 11 days see rain.

rain gear

Sea temperature near Castro-Urdiales in September

The nearest coast averages about 20°C in September — 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 September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 5 — enough to warrant sun protection. 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
September 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).