Swansea weather in September

In September, Swansea sees average daytime highs of 17°C and overnight lows near 13°C, with 96 mm of rain across 13.2 wet days and about 12.4 hours of daylight. It is the 3rd-warmest and 6th-wettest month of the year here.

Highs ease over the month, from about 17°C in the first days to 16°C by the end. The sky is clear or mostly clear about 17% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 24 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Swansea's 6th-clearest and 7th-windiest month. For the whole year in context, see Swansea's year-round climate.

Daytime high: 17°; 3rd warmest
Overnight low: 13°; 10th coldest
Rainfall: 96 mm; 13.2 wet days
Daylight: 12 h 24 min; 5:58 AM – 6:22 PM
Cloud cover: 68%; 6th clearest
Wind: 21 km/h; 7th windiest
Solar energy: 3.2 kWh/m²
Travel score: 4.8; out of 10

Swansea is city in Wales.

Air quality: Good; PM2.5 9.9 µg/m³ · 2019
Founded: 1158

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

← August Swansea year-round climate October →Best places to visit in September

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 17°C in the first days to 16°C by the end.

A typical September day in Swansea reaches about 17°C in the afternoon and slips back to 13°C overnight — a 4°C spread between the day's warmth and the night's chill. On most days the high lands between 14°C and 19°C. Set against its neighbours, September runs about 1°C cooler than August and about 3°C warmer than October.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Avg high (°C)	17	17	17	17	17	17	17	17	17	17	17	17	17	17	17	17	17	17	16	16	16	16	16	16	16	16	16	16	16	15
Avg low (°C)	14	14	14	14	14	14	14	14	14	14	13	13	13	13	13	13	13	13	13	13	13	13	13	13	13	13	13	12	12	12

	Avg high (°C)	Avg low (°C)
1	17	14
2	17	14
3	17	14
4	17	14
5	17	14
6	17	14
7	17	14
8	17	14
9	17	14
10	17	14
11	17	13
12	17	13
13	17	13
14	17	13
15	17	13
16	17	13
17	17	13
18	17	13
19	16	13
20	16	13
21	16	13
22	16	13
23	16	13
24	16	13
25	16	13
26	16	13
27	16	13
28	16	12
29	16	12
30	15	12

Swansea weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 6th-wettest month here — the current month is highlighted below.

Month	High / Low (°C)	Rainfall (mm)	Wet days	Snow days	Daylight (hours)	Travel score
Jan	8° / 5°	128	17	0.4	8.1	1.1
Feb	8° / 5°	90	13	0.6	9.6	1.1
Mar	9° / 6°	83	13.7	0.3	11.5	1.6
Apr	11° / 7°	69	12	0.1	13.6	2.5
May	13° / 10°	72	12.4	0	15.3	3.6
Jun	16° / 12°	79	12.2	0	16.3	4.6
Jul	18° / 14°	86	13.8	0	15.9	5.2
Aug	18° / 15°	101	14.3	0	14.4	5.2
Sep	17° / 13°	96	13.2	0	12.4	4.8
Oct	14° / 11°	143	16.7	0	10.4	3.4
Nov	11° / 8°	143	17.3	0	8.6	2.2
Dec	9° / 6°	145	16.8	0.3	7.7	1.4

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 17% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 19% of September, with mostly cloudy or overcast conditions the remaining 64%.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Clearer (%)	37	38	38	38	37	38	38	38	39	39	39	39	39	39	38	38	38	37	36	35	35	34	33	32	32	32	31	31	29	29
Cloudier (%)	63	62	62	62	63	62	62	62	61	61	61	61	61	61	62	62	62	63	64	65	65	66	67	68	68	68	69	69	71	71

	Clearer (%)	Cloudier (%)
1	37	63
2	38	62
3	38	62
4	38	62
5	37	63
6	38	62
7	38	62
8	38	62
9	39	61
10	39	61
11	39	61
12	39	61
13	39	61
14	39	61
15	38	62
16	38	62
17	38	62
18	37	63
19	36	64
20	35	65
21	35	65
22	34	66
23	33	67
24	32	68
25	32	68
26	32	68
27	31	69
28	31	69
29	29	71
30	29	71

Chance of precipitation in September

Any precipitation

Swansea gets around 96 mm of rain over 13.2 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 44% and peaks near 52% on the wettest days. The odds climb toward the end of the month.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Rain chance (%)	39	39	39	39	40	40	41	41	41	42	42	42	43	43	43	44	44	44	44	45	45	46	47	48	49	50	51	51	52	52

	Rain chance (%)
1	39
2	39
3	39
4	39
5	40
6	40
7	41
8	41
9	41
10	42
11	42
12	42
13	43
14	43
15	43
16	44
17	44
18	44
19	44
20	45
21	45
22	46
23	47
24	48
25	49
26	50
27	51
28	51
29	52
30	52

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 69% of days. It rarely turns muggy — the humid and sticky bands barely register.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Dry (%)	57	58	59	60	61	62	63	64	65	66	67	68	70	70	72	72	73	74	74	73	74	74	74	74	75	75	76	77	77	79
Comfortable (%)	38	37	36	35	34	33	32	31	30	29	28	27	26	26	25	25	24	24	24	25	25	25	25	25	24	24	23	22	22	21
Humid (%)	5	5	5	5	5	5	5	5	5	5	5	5	4	4	3	3	3	2	2	2	1	1	1	1	1	1	1	1	1	0

	Dry (%)	Comfortable (%)	Humid (%)
1	57	38	5
2	58	37	5
3	59	36	5
4	60	35	5
5	61	34	5
6	62	33	5
7	63	32	5
8	64	31	5
9	65	30	5
10	66	29	5
11	67	28	5
12	68	27	5
13	70	26	4
14	70	26	4
15	72	25	3
16	72	25	3
17	73	24	3
18	74	24	2
19	74	24	2
20	73	25	2
21	74	25	1
22	74	25	1
23	74	25	1
24	74	25	1
25	75	24	1
26	75	24	1
27	76	23	1
28	77	22	1
29	77	22	1
30	79	21	0

Wind in September

Winds average 21 km/h in September.

Across September, daily wind ranges from about 20 km/h on the calmest days to 22 km/h at its breeziest. It stays fairly steady from day to day.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Wind speed (km/h)	20	20	20	20	20	20	20	20	20	21	21	21	21	21	21	21	21	21	21	21	21	21	21	21	22	22	22	22	22	22
Feels	light breeze	light breeze	light breeze	light breeze	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy	breezy

	Wind speed (km/h)	Feels
1	20	light breeze
2	20	light breeze
3	20	light breeze
4	20	light breeze
5	20	breezy
6	20	breezy
7	20	breezy
8	20	breezy
9	20	breezy
10	21	breezy
11	21	breezy
12	21	breezy
13	21	breezy
14	21	breezy
15	21	breezy
16	21	breezy
17	21	breezy
18	21	breezy
19	21	breezy
20	21	breezy
21	21	breezy
22	21	breezy
23	21	breezy
24	21	breezy
25	22	breezy
26	22	breezy
27	22	breezy
28	22	breezy
29	22	breezy
30	22	breezy

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 24 min at the start of September to 11 h 24 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 120 minutes over September. Sunrise moves from 5:34 AM to 6:22 AM, and sunset from 6:57 PM to 5:48 PM.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Daylight (h)	13.4	13.3	13.3	13.2	13.1	13.1	13.0	12.9	12.9	12.8	12.7	12.7	12.6	12.5	12.5	12.4	12.3	12.3	12.2	12.1	12.1	12.0	11.9	11.8	11.8	11.7	11.6	11.6	11.5	11.4
Sunrise (AM)	5:34	5:35	5:37	5:39	5:40	5:42	5:43	5:45	5:47	5:48	5:50	5:52	5:53	5:55	5:57	5:58	6:00	6:02	6:03	6:05	6:07	6:08	6:10	6:12	6:13	6:15	6:17	6:18	6:20	6:22
Sunset (PM)	6:57	6:55	6:53	6:50	6:48	6:46	6:43	6:41	6:39	6:36	6:34	6:31	6:29	6:27	6:24	6:22	6:19	6:17	6:15	6:12	6:10	6:07	6:05	6:03	6:00	5:58	5:55	5:53	5:51	5:48

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.4	5:34	6:57
2	13.3	5:35	6:55
3	13.3	5:37	6:53
4	13.2	5:39	6:50
5	13.1	5:40	6:48
6	13.1	5:42	6:46
7	13.0	5:43	6:43
8	12.9	5:45	6:41
9	12.9	5:47	6:39
10	12.8	5:48	6:36
11	12.7	5:50	6:34
12	12.7	5:52	6:31
13	12.6	5:53	6:29
14	12.5	5:55	6:27
15	12.5	5:57	6:24
16	12.4	5:58	6:22
17	12.3	6:00	6:19
18	12.3	6:02	6:17
19	12.2	6:03	6:15
20	12.1	6:05	6:12
21	12.1	6:07	6:10
22	12.0	6:08	6:07
23	11.9	6:10	6:05
24	11.8	6:12	6:03
25	11.8	6:13	6:00
26	11.7	6:15	5:58
27	11.6	6:17	5:55
28	11.6	6:18	5:53
29	11.5	6:20	5:51
30	11.4	6:22	5:48

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.2 kWh/m².

For context, solar energy here swings from a low near 0.65 kWh/m² to a high of 5.63 kWh/m² in June across the year — September's 3.2 kWh/m² falls in the middle.

	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20	21	22	23	24	25	26	27	28	29	30
Solar energy (kWh/m²)	3.9	3.8	3.8	3.7	3.7	3.6	3.6	3.6	3.5	3.5	3.4	3.4	3.4	3.3	3.3	3.2	3.2	3.1	3.1	3.0	3.0	2.9	2.9	2.8	2.7	2.7	2.6	2.6	2.5	2.5
Level	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate	Moderate

	Solar energy (kWh/m²)	Level
1	3.9	Moderate
2	3.8	Moderate
3	3.8	Moderate
4	3.7	Moderate
5	3.7	Moderate
6	3.6	Moderate
7	3.6	Moderate
8	3.6	Moderate
9	3.5	Moderate
10	3.5	Moderate
11	3.4	Moderate
12	3.4	Moderate
13	3.4	Moderate
14	3.3	Moderate
15	3.3	Moderate
16	3.2	Moderate
17	3.2	Moderate
18	3.1	Moderate
19	3.1	Moderate
20	3.0	Moderate
21	3.0	Moderate
22	2.9	Moderate
23	2.9	Moderate
24	2.8	Moderate
25	2.7	Moderate
26	2.7	Moderate
27	2.6	Moderate
28	2.6	Moderate
29	2.5	Moderate
30	2.5	Moderate

Planning a trip in September

Is September a good time to visit Swansea?

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

4.8

Sightseeing

3rd-best month of the year

0.9

Beach & pool

3rd-best month of the year

September is a reasonable time to visit Swansea for sightseeing.

What to pack for Swansea in September

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

In September, Swansea sees daytime highs around 17°C and nights near 13°C. Worth packing: a warm layer, rain gear and a windbreaker. About 13 days see rain.

a warm layerrain geara windbreaker

Sea temperature near Swansea in September

The nearest coast averages about 17°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 18°C and coldest in February near 8°C.

The water stays below 20°C all year — cool enough that most swimmers want a wetsuit.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Sea temperature (°C)	8	8	8	9	11	14	16	18	17	15	12	10
Comfort	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Cool	Cool	Cool	Cool	Bracing	Bracing

	Sea temperature (°C)	Comfort
Jan	8	Bracing
Feb	8	Bracing
Mar	8	Bracing
Apr	9	Bracing
May	11	Bracing
Jun	14	Bracing
Jul	16	Cool
Aug	18	Cool
Sep	17	Cool
Oct	15	Cool
Nov	12	Bracing
Dec	10	Bracing

UV index in Swansea in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 4 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Swansea peaks around August 13 at about 6 (high) — sunscreen and a hat are worth it in the middle of the day. It bottoms out near January 1 at about 1 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 6 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	1	1	3	4	6	6	6	7	4	2	1	1
Level	Low	Low	Moderate	Moderate	High	High	High	High	Moderate	Moderate	Low	Low

	UV index (midday)	Level
Jan	1	Low
Feb	1	Low
Mar	3	Moderate
Apr	4	Moderate
May	6	High
Jun	6	High
Jul	6	High
Aug	7	High
Sep	4	Moderate
Oct	2	Moderate
Nov	1	Low
Dec	1	Low

Location & terrain

Where is Swansea?

Swansea sits at 51.6°N, 3.9°W, 18 m above sea level, in United Kingdom. The nearest listed city is Clydach, 8.0 km away.

Topography around Swansea

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

Within 3 km, the terrain around Swansea has only modest variations in elevation — a maximum elevation change of 194 m around an average of 44 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 422 m; within 80 km, large variations in elevation — a maximum elevation change of 878 m.

The land around Swansea is covered by artificial surfaces (34%), water (32%) and trees (23%) within 3 km, water (35%), grassland (28%) and trees (26%) within 16 km, and grassland (46%) and water (35%) within 80 km.

3 km

194 m

artificial surfaces 34%

16 km

422 m

water 35%

80 km

878 m

grassland 46%

treesgrasslandcroplandartificial surfacesbare terrainwaterwetland

← August Swansea year-round climate October →Best places to visit in September

September weather nearby: Clydach 8.0 km · Briton Ferry 9.0 km · Gorseinon 9.0 km · Neath 11 km · Llanelli 17 km · Ammanford 19 km · Maesteg 20 km · Porthcawl 23 km

United Kingdom travel facts

Travel advisory: Level 2; Exercise Increased Caution
Power plugs: Type D / G / M; 230 V · 50 Hz
Prices: ≈ 89% of US; price level, 2025
GDP per capita: $57,602; 2025
Happiness: 6.7 / 10; World Happiness, 2025
Safe drinking water: 100%; of population, 2024
Homicide rate: 1.1; per 100k, 2021
Road deaths: 3.2; per 100k/yr, 2019
Income group: High; World Bank
Religion

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 Swansea (51.6208°, -3.9432°, 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).

	Avg high (°C)	Avg low (°C)
1	17	14
2	17	14
3	17	14
4	17	14
5	17	14
6	17	14
7	17	14
8	17	14
9	17	14
10	17	14
11	17	13
12	17	13
13	17	13
14	17	13
15	17	13
16	17	13
17	17	13
18	17	13
19	16	13
20	16	13
21	16	13
22	16	13
23	16	13
24	16	13
25	16	13
26	16	13
27	16	13
28	16	12
29	16	12
30	15	12

	Clearer (%)	Cloudier (%)
1	37	63
2	38	62
3	38	62
4	38	62
5	37	63
6	38	62
7	38	62
8	38	62
9	39	61
10	39	61
11	39	61
12	39	61
13	39	61
14	39	61
15	38	62
16	38	62
17	38	62
18	37	63
19	36	64
20	35	65
21	35	65
22	34	66
23	33	67
24	32	68
25	32	68
26	32	68
27	31	69
28	31	69
29	29	71
30	29	71

	Rain chance (%)
1	39
2	39
3	39
4	39
5	40
6	40
7	41
8	41
9	41
10	42
11	42
12	42
13	43
14	43
15	43
16	44
17	44
18	44
19	44
20	45
21	45
22	46
23	47
24	48
25	49
26	50
27	51
28	51
29	52
30	52

	Dry (%)	Comfortable (%)	Humid (%)
1	57	38	5
2	58	37	5
3	59	36	5
4	60	35	5
5	61	34	5
6	62	33	5
7	63	32	5
8	64	31	5
9	65	30	5
10	66	29	5
11	67	28	5
12	68	27	5
13	70	26	4
14	70	26	4
15	72	25	3
16	72	25	3
17	73	24	3
18	74	24	2
19	74	24	2
20	73	25	2
21	74	25	1
22	74	25	1
23	74	25	1
24	74	25	1
25	75	24	1
26	75	24	1
27	76	23	1
28	77	22	1
29	77	22	1
30	79	21	0

	Avg high (°C)	Avg low (°C)
1	17	14
2	17	14
3	17	14
4	17	14
5	17	14
6	17	14
7	17	14
8	17	14
9	17	14
10	17	14
11	17	13
12	17	13
13	17	13
14	17	13
15	17	13
16	17	13
17	17	13
18	17	13
19	16	13
20	16	13
21	16	13
22	16	13
23	16	13
24	16	13
25	16	13
26	16	13
27	16	13
28	16	12
29	16	12
30	15	12

	Clearer (%)	Cloudier (%)
1	37	63
2	38	62
3	38	62
4	38	62
5	37	63
6	38	62
7	38	62
8	38	62
9	39	61
10	39	61
11	39	61
12	39	61
13	39	61
14	39	61
15	38	62
16	38	62
17	38	62
18	37	63
19	36	64
20	35	65
21	35	65
22	34	66
23	33	67
24	32	68
25	32	68
26	32	68
27	31	69
28	31	69
29	29	71
30	29	71

	Rain chance (%)
1	39
2	39
3	39
4	39
5	40
6	40
7	41
8	41
9	41
10	42
11	42
12	42
13	43
14	43
15	43
16	44
17	44
18	44
19	44
20	45
21	45
22	46
23	47
24	48
25	49
26	50
27	51
28	51
29	52
30	52

	Dry (%)	Comfortable (%)	Humid (%)
1	57	38	5
2	58	37	5
3	59	36	5
4	60	35	5
5	61	34	5
6	62	33	5
7	63	32	5
8	64	31	5
9	65	30	5
10	66	29	5
11	67	28	5
12	68	27	5
13	70	26	4
14	70	26	4
15	72	25	3
16	72	25	3
17	73	24	3
18	74	24	2
19	74	24	2
20	73	25	2
21	74	25	1
22	74	25	1
23	74	25	1
24	74	25	1
25	75	24	1
26	75	24	1
27	76	23	1
28	77	22	1
29	77	22	1
30	79	21	0

	Avg high (°C)	Avg low (°C)
1	17	14
2	17	14
3	17	14
4	17	14
5	17	14
6	17	14
7	17	14
8	17	14
9	17	14
10	17	14
11	17	13
12	17	13
13	17	13
14	17	13
15	17	13
16	17	13
17	17	13
18	17	13
19	16	13
20	16	13
21	16	13
22	16	13
23	16	13
24	16	13
25	16	13
26	16	13
27	16	13
28	16	12
29	16	12
30	15	12

	Clearer (%)	Cloudier (%)
1	37	63
2	38	62
3	38	62
4	38	62
5	37	63
6	38	62
7	38	62
8	38	62
9	39	61
10	39	61
11	39	61
12	39	61
13	39	61
14	39	61
15	38	62
16	38	62
17	38	62
18	37	63
19	36	64
20	35	65
21	35	65
22	34	66
23	33	67
24	32	68
25	32	68
26	32	68
27	31	69
28	31	69
29	29	71
30	29	71

	Rain chance (%)
1	39
2	39
3	39
4	39
5	40
6	40
7	41
8	41
9	41
10	42
11	42
12	42
13	43
14	43
15	43
16	44
17	44
18	44
19	44
20	45
21	45
22	46
23	47
24	48
25	49
26	50
27	51
28	51
29	52
30	52

	Dry (%)	Comfortable (%)	Humid (%)
1	57	38	5
2	58	37	5
3	59	36	5
4	60	35	5
5	61	34	5
6	62	33	5
7	63	32	5
8	64	31	5
9	65	30	5
10	66	29	5
11	67	28	5
12	68	27	5
13	70	26	4
14	70	26	4
15	72	25	3
16	72	25	3
17	73	24	3
18	74	24	2
19	74	24	2
20	73	25	2
21	74	25	1
22	74	25	1
23	74	25	1
24	74	25	1
25	75	24	1
26	75	24	1
27	76	23	1
28	77	22	1
29	77	22	1
30	79	21	0