Coleraine weather in September

In September, Coleraine sees average daytime highs of 14°C and overnight lows near 12°C, with 101 mm of rain across 16.3 wet days and about 12.5 hours of daylight. It is the 2nd-warmest and 6th-wettest month of the year here.

Day-to-day highs hold fairly steady near 14°C through the month. The sky is clear or mostly clear about 9% of the time in September, and the air most often feels dry.

Daylight stretches from about 13 h 36 min at the start of September to 11 h 24 min by month's end. Set against the rest of the year, September is Coleraine's 5th-clearest and 7th-windiest month. For the whole year in context, see Coleraine's year-round climate.

Daytime high: 14°; 2nd warmest
Overnight low: 12°; 10th coldest
Rainfall: 101 mm; 16.3 wet days
Daylight: 12 h 24 min; 6:08 AM – 6:34 PM
Cloud cover: 75%; 5th clearest
Wind: 25 km/h; 7th windiest
Solar energy: 2.63 kWh/m²
Travel score: 3.5; out of 10

Coleraine is town and civil parish in County Londonderry, Northern Ireland.

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

← August Coleraine 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

Day-to-day highs hold fairly steady near 14°C through the month.

A typical September day in Coleraine reaches about 14°C in the afternoon and slips back to 12°C overnight — a 2°C spread between the day's warmth and the night's chill. On most days the high lands between 12°C and 16°C. Set against its neighbours, September runs on par with August and about 2°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)	15	15	15	15	15	15	15	15	15	15	15	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14	14
Avg low (°C)	13	13	13	13	13	13	13	13	13	13	13	13	12	12	12	12	12	12	12	12	12	12	12	12	12	12	12	12	12	12

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

Coleraine weather by month

How September compares with the rest of the year at a glance. September is the 2nd-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° / 6°	124	20.3	0.6	7.5	1.0
Feb	8° / 5°	100	16.9	1	9.2	0.9
Mar	8° / 6°	91	16	0.8	11.4	1.1
Apr	9° / 7°	78	13.9	0.2	13.8	1.6
May	11° / 9°	71	13.4	0	15.8	2.3
Jun	13° / 11°	86	14.6	0	17	2.9
Jul	14° / 13°	95	16.1	0	16.5	3.5
Aug	15° / 13°	104	16.2	0	14.7	3.7
Sep	14° / 12°	101	16.3	0	12.5	3.5
Oct	12° / 10°	139	18.9	0	10.2	2.6
Nov	10° / 8°	149	20.8	0.2	8.1	1.7
Dec	9° / 6°	147	20	0.7	7	1.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 9% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 18% of September, with mostly cloudy or overcast conditions the remaining 73%.

	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 (%)	29	29	28	28	27	27	27	27	27	27	27	27	27	27	27	27	28	28	28	28	28	28	27	27	27	27	27	27	27	27
Cloudier (%)	71	71	72	72	73	73	73	73	73	73	73	73	73	73	73	73	72	72	72	72	72	72	73	73	73	73	73	73	73	73

	Clearer (%)	Cloudier (%)
1	29	71
2	29	71
3	28	72
4	28	72
5	27	73
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	27	73
12	27	73
13	27	73
14	27	73
15	27	73
16	27	73
17	28	72
18	28	72
19	28	72
20	28	72
21	28	72
22	28	72
23	27	73
24	27	73
25	27	73
26	27	73
27	27	73
28	27	73
29	27	73
30	27	73

Chance of precipitation in September

Any precipitation

Coleraine gets around 101 mm of rain over 16.3 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 54% and peaks near 59% on the wettest days.

	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 (%)	51	51	52	52	53	54	54	55	55	55	55	55	55	55	54	54	54	54	53	53	53	54	54	55	55	56	57	58	58	59

	Rain chance (%)
1	51
2	51
3	52
4	52
5	53
6	54
7	54
8	55
9	55
10	55
11	55
12	55
13	55
14	55
15	54
16	54
17	54
18	54
19	53
20	53
21	53
22	54
23	54
24	55
25	55
26	56
27	57
28	58
29	58
30	59

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 89% 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 (%)	84	84	84	85	85	85	85	85	86	86	87	88	88	89	89	90	90	91	91	91	92	92	93	93	93	94	94	94	95	95
Comfortable (%)	16	16	16	15	15	15	15	15	14	14	13	12	12	11	11	10	10	9	9	9	8	8	7	7	7	6	6	6	5	5

	Dry (%)	Comfortable (%)
1	84	16
2	84	16
3	84	16
4	85	15
5	85	15
6	85	15
7	85	15
8	85	15
9	86	14
10	86	14
11	87	13
12	88	12
13	88	12
14	89	11
15	89	11
16	90	10
17	90	10
18	91	9
19	91	9
20	91	9
21	92	8
22	92	8
23	93	7
24	93	7
25	93	7
26	94	6
27	94	6
28	94	6
29	95	5
30	95	5

Wind in September

Winds average 25 km/h in September.

Across September, daily wind ranges from about 23 km/h on the calmest days to 27 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)	23	24	24	24	24	24	25	25	25	25	25	25	25	25	25	25	25	25	25	26	26	26	26	26	26	26	26	27	27	27
Feels	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	breezy	breezy	breezy	breezy

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

Sunrise & sunset in September

DaylightNight

Daylight runs from about 13 h 36 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 132 minutes over September. Sunrise moves from 5:39 AM to 6:35 AM, and sunset from 7:14 PM to 5:57 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)	13.6	13.5	13.4	13.4	13.3	13.2	13.1	13.1	13.0	12.9	12.8	12.8	12.7	12.6	12.5	12.4	12.4	12.3	12.2	12.1	12.1	12.0	11.9	11.8	11.7	11.7	11.6	11.5	11.4	11.4
Sunrise (AM)	5:39	5:41	5:43	5:44	5:46	5:48	5:50	5:52	5:54	5:56	5:58	6:00	6:02	6:04	6:06	6:08	6:10	6:12	6:14	6:15	6:17	6:19	6:21	6:23	6:25	6:27	6:29	6:31	6:33	6:35
Sunset (PM)	7:14	7:11	7:09	7:06	7:04	7:01	6:58	6:56	6:53	6:50	6:48	6:45	6:42	6:40	6:37	6:34	6:32	6:29	6:26	6:24	6:21	6:18	6:16	6:13	6:10	6:07	6:05	6:02	6:00	5:57

	Daylight (h)	Sunrise (AM)	Sunset (PM)
1	13.6	5:39	7:14
2	13.5	5:41	7:11
3	13.4	5:43	7:09
4	13.4	5:44	7:06
5	13.3	5:46	7:04
6	13.2	5:48	7:01
7	13.1	5:50	6:58
8	13.1	5:52	6:56
9	13.0	5:54	6:53
10	12.9	5:56	6:50
11	12.8	5:58	6:48
12	12.8	6:00	6:45
13	12.7	6:02	6:42
14	12.6	6:04	6:40
15	12.5	6:06	6:37
16	12.4	6:08	6:34
17	12.4	6:10	6:32
18	12.3	6:12	6:29
19	12.2	6:14	6:26
20	12.1	6:15	6:24
21	12.1	6:17	6:21
22	12.0	6:19	6:18
23	11.9	6:21	6:16
24	11.8	6:23	6:13
25	11.7	6:25	6:10
26	11.7	6:27	6:07
27	11.6	6:29	6:05
28	11.5	6:31	6:02
29	11.4	6:33	6:00
30	11.4	6:35	5:57

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 2.63 kWh/m².

For context, solar energy here swings from a low near 0.41 kWh/m² to a high of 5 kWh/m² in May across the year — September's 2.63 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)	3.2	3.2	3.1	3.1	3.0	3.0	3.0	2.9	2.9	2.9	2.8	2.8	2.7	2.7	2.7	2.6	2.6	2.6	2.5	2.5	2.4	2.4	2.4	2.3	2.3	2.2	2.2	2.1	2.1	2.0
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	3.2	Moderate
2	3.2	Moderate
3	3.1	Moderate
4	3.1	Moderate
5	3.0	Moderate
6	3.0	Moderate
7	3.0	Moderate
8	2.9	Moderate
9	2.9	Moderate
10	2.9	Moderate
11	2.8	Moderate
12	2.8	Moderate
13	2.7	Moderate
14	2.7	Moderate
15	2.7	Moderate
16	2.6	Moderate
17	2.6	Moderate
18	2.6	Moderate
19	2.5	Moderate
20	2.5	Moderate
21	2.4	Moderate
22	2.4	Moderate
23	2.4	Moderate
24	2.3	Moderate
25	2.3	Moderate
26	2.2	Moderate
27	2.2	Moderate
28	2.1	Moderate
29	2.1	Moderate
30	2.0	Moderate

Planning a trip in September

Is September a good time to visit Coleraine?

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

3.5

Sightseeing

2nd-best month of the year

—

Beach & pool

never really warm enough

September is a weaker month for outdoor sightseeing in Coleraine.

What to pack for Coleraine in September

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

In September, Coleraine sees daytime highs around 14°C and nights near 12°C. Pack rain gear. Worth having: a warm layer and a windbreaker. About 16 days see rain.

rain geara warm layera windbreaker

Sea temperature near Coleraine in September

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

The sea at the nearest coast (about 27 km away) is warmest in September at about 14°C and coldest in March 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)	9	8	8	8	9	11	13	14	14	13	12	10
Comfort	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing	Bracing

	Sea temperature (°C)	Comfort
Jan	9	Bracing
Feb	8	Bracing
Mar	8	Bracing
Apr	8	Bracing
May	9	Bracing
Jun	11	Bracing
Jul	13	Bracing
Aug	14	Bracing
Sep	14	Bracing
Oct	13	Bracing
Nov	12	Bracing
Dec	10	Bracing

UV index in Coleraine in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 3 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Coleraine peaks around July 12 at about 5 (high) — a little sun protection helps at midday. It bottoms out near January 1 at about 0 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 5 months of the year.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
UV index (midday)	0	1	2	3	5	5	5	4	3	2	1	0
Level	Low	Low	Moderate	Moderate	High	Moderate	High	Moderate	Moderate	Low	Low	Low

	UV index (midday)	Level
Jan	0	Low
Feb	1	Low
Mar	2	Moderate
Apr	3	Moderate
May	5	High
Jun	5	Moderate
Jul	5	High
Aug	4	Moderate
Sep	3	Moderate
Oct	2	Low
Nov	1	Low
Dec	0	Low

Location & terrain

Where is Coleraine?

Coleraine sits at 55.1°N, 6.7°W, 5 m above sea level, in United Kingdom. The nearest listed city is Ballymena, 39 km away.

Topography around Coleraine

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

Within 3 km, the terrain around Coleraine has only modest variations in elevation — a maximum elevation change of 82 m around an average of 30 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 385 m; within 80 km, large variations in elevation — a maximum elevation change of 675 m.

The land around Coleraine is covered by grassland (54%) and trees (22%) within 3 km, grassland (57%) and water (24%) within 16 km, and grassland (46%) and water (46%) within 80 km.

3 km

82 m

grassland 54%

16 km

385 m

grassland 57%

80 km

675 m

grassland 46%

treesgrasslandcroplandartificial surfaceswater

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

September weather nearby: Ballymena 39 km · Derry 44 km · Londonderry County Borough 44 km · Antrim 55 km · Larne 63 km · Letterkenny 71 km · Newtownabbey 72 km · Omagh 72 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 Coleraine (55.1333°, -6.6667°, elevation 5 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	15	13
2	15	13
3	15	13
4	15	13
5	15	13
6	15	13
7	15	13
8	15	13
9	15	13
10	15	13
11	15	13
12	14	13
13	14	12
14	14	12
15	14	12
16	14	12
17	14	12
18	14	12
19	14	12
20	14	12
21	14	12
22	14	12
23	14	12
24	14	12
25	14	12
26	14	12
27	14	12
28	14	12
29	14	12
30	14	12

	Clearer (%)	Cloudier (%)
1	29	71
2	29	71
3	28	72
4	28	72
5	27	73
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	27	73
12	27	73
13	27	73
14	27	73
15	27	73
16	27	73
17	28	72
18	28	72
19	28	72
20	28	72
21	28	72
22	28	72
23	27	73
24	27	73
25	27	73
26	27	73
27	27	73
28	27	73
29	27	73
30	27	73

	Rain chance (%)
1	51
2	51
3	52
4	52
5	53
6	54
7	54
8	55
9	55
10	55
11	55
12	55
13	55
14	55
15	54
16	54
17	54
18	54
19	53
20	53
21	53
22	54
23	54
24	55
25	55
26	56
27	57
28	58
29	58
30	59

	Dry (%)	Comfortable (%)
1	84	16
2	84	16
3	84	16
4	85	15
5	85	15
6	85	15
7	85	15
8	85	15
9	86	14
10	86	14
11	87	13
12	88	12
13	88	12
14	89	11
15	89	11
16	90	10
17	90	10
18	91	9
19	91	9
20	91	9
21	92	8
22	92	8
23	93	7
24	93	7
25	93	7
26	94	6
27	94	6
28	94	6
29	95	5
30	95	5

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

	Clearer (%)	Cloudier (%)
1	29	71
2	29	71
3	28	72
4	28	72
5	27	73
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	27	73
12	27	73
13	27	73
14	27	73
15	27	73
16	27	73
17	28	72
18	28	72
19	28	72
20	28	72
21	28	72
22	28	72
23	27	73
24	27	73
25	27	73
26	27	73
27	27	73
28	27	73
29	27	73
30	27	73

	Rain chance (%)
1	51
2	51
3	52
4	52
5	53
6	54
7	54
8	55
9	55
10	55
11	55
12	55
13	55
14	55
15	54
16	54
17	54
18	54
19	53
20	53
21	53
22	54
23	54
24	55
25	55
26	56
27	57
28	58
29	58
30	59

	Dry (%)	Comfortable (%)
1	84	16
2	84	16
3	84	16
4	85	15
5	85	15
6	85	15
7	85	15
8	85	15
9	86	14
10	86	14
11	87	13
12	88	12
13	88	12
14	89	11
15	89	11
16	90	10
17	90	10
18	91	9
19	91	9
20	91	9
21	92	8
22	92	8
23	93	7
24	93	7
25	93	7
26	94	6
27	94	6
28	94	6
29	95	5
30	95	5

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

	Clearer (%)	Cloudier (%)
1	29	71
2	29	71
3	28	72
4	28	72
5	27	73
6	27	73
7	27	73
8	27	73
9	27	73
10	27	73
11	27	73
12	27	73
13	27	73
14	27	73
15	27	73
16	27	73
17	28	72
18	28	72
19	28	72
20	28	72
21	28	72
22	28	72
23	27	73
24	27	73
25	27	73
26	27	73
27	27	73
28	27	73
29	27	73
30	27	73

	Rain chance (%)
1	51
2	51
3	52
4	52
5	53
6	54
7	54
8	55
9	55
10	55
11	55
12	55
13	55
14	55
15	54
16	54
17	54
18	54
19	53
20	53
21	53
22	54
23	54
24	55
25	55
26	56
27	57
28	58
29	58
30	59

	Dry (%)	Comfortable (%)
1	84	16
2	84	16
3	84	16
4	85	15
5	85	15
6	85	15
7	85	15
8	85	15
9	86	14
10	86	14
11	87	13
12	88	12
13	88	12
14	89	11
15	89	11
16	90	10
17	90	10
18	91	9
19	91	9
20	91	9
21	92	8
22	92	8
23	93	7
24	93	7
25	93	7
26	94	6
27	94	6
28	94	6
29	95	5
30	95	5