Where is the sea coldest in Ireland in September?

Inchydoney in Ireland has the coldest sea in Ireland in September, averaging about 15.0 °C. Derrynane (15.0 °C) and Inch Beach are the next coolest.

How many beaches in Ireland are warm enough to swim in September?

None of the top 25 ranked beaches in Ireland reach 22 °C in September, so a wetsuit is recommended for anything longer than a quick dip.

How are these September sea temperatures calculated?

Each figure is a long-term monthly average sea surface temperature for that location, so it reflects a typical September rather than today's reading. Open a beach page for the live water temperature and 7-day forecast.

Seasonal ranking

Coldest sea temperature in Ireland in September

Where the sea is coolest across Ireland during September, ranked by long-term monthly average water temperature. Inchydoney (West Coast, Ireland) is the coolest at around 15°C. Open any spot for today's live water temperature and a 7-day swim forecast.

1
Inchydoney
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
2
Derrynane
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
3
Inch Beach
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
4
Fanore
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
5
Keem Bay
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
6
Dog's Bay
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
7
Streedagh
West Coast · Ireland · Celtic Sea
Cool — shorty wetsuit recommended
15°C
September average
8
Brittas Bay
East Coast · Ireland · Irish Sea
Cool — shorty wetsuit recommended
15°C
September average
9
Curracloe
East Coast · Ireland · Irish Sea
Cool — shorty wetsuit recommended
15°C
September average
10
Portmarnock
East Coast · Ireland · Irish Sea
Cool — shorty wetsuit recommended
15°C
September average
11
Seapoint
County Dublin · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
12
Sandycove
County Dublin · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
13
Forty Foot
County Dublin · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
14
Donabate Beach
County Dublin · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
15
Balbriggan Front Strand
County Dublin · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
16
Bettystown Beach
County Meath · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
17
Laytown Beach
County Meath · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
18
Templetown Beach
County Louth · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
19
Cranfield Beach
County Down · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
20
Tyrella Beach
County Down · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
21
Murlough Beach
County Down · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
22
Benone Strand
County Londonderry · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
23
Portstewart Strand
County Londonderry · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
24
Whiterocks Beach
County Antrim · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average
25
Ballycastle Beach
County Antrim · Ireland · Atlantic Ocean
Cool — shorty wetsuit recommended
15°C
September average

Coldest sea in September elsewhere

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Ireland in September — frequently asked questions

Where is the sea coldest in Ireland in September?: Inchydoney in Ireland has the coldest sea in Ireland in September, averaging about 15.0 °C. Derrynane (15.0 °C) and Inch Beach are the next coolest.
How many beaches in Ireland are warm enough to swim in September?: None of the top 25 ranked beaches in Ireland reach 22 °C in September, so a wetsuit is recommended for anything longer than a quick dip.
How are these September sea temperatures calculated?: Each figure is a long-term monthly average sea surface temperature for that location, so it reflects a typical September rather than today's reading. Open a beach page for the live water temperature and 7-day forecast.

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