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Coldest sea in Ireland in September

169 coastal locations in Ireland ranked by typical September sea temperature, coldest first. Region-wide average in September: 15.4°C.

Coldest in September

Moville

14.7°C September mean in Ireland

Regional September average

15.4°C

across all 169 coastal locations in Ireland

Vs annual mean

+3.1°C

above the year-round regional average

What the Ireland sea feels like in September

At this temperature, water will feel cold compared to a swimming pool, but with a bit of experience and practice most people will find the water relatively comfortable to swim in.

Ireland monthly average 9.0°C to 16.0°C
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  • Warmest month August 16.0°C
  • Coldest month February 9.0°C
  • Annual mean 12.3°C
  • Months above 20°C 0 of 12

Where September fits in the year

September sits inside the regional pattern shown on the left. Pick a different month to see how the ranking shifts.

All twelve Ireland month rankings:

Ireland sea temperature map (live)

The map shows today's latest reading at every Ireland location. The list below is based on the typical September mean.

Zoom in to see individual locations. Click a pin for water temperatures. View list →
°C -2 0 1 3 5 7 9 11 13 15 17 19 21 24 27 30 35

Top 50 coldest Ireland locations in September

Sorted by typical September mean from a decade of daily readings, coldest first. Click any place for the full location page.

# Location September mean
1 Moville 14.7°C
2 Buncrana 14.8°C
3 Inishtrahull County Donegal 14.8°C
4 Belmullet 14.8°C
5 Blackrock 14.8°C
6 Clogherhead 14.8°C
7 Dalkey 14.8°C
8 Donabate 14.8°C
9 Dun Laoghaire 14.8°C
10 Forty Foot 14.8°C
11 Howth 14.8°C
12 Killiney 14.8°C
13 Malahide 14.8°C
14 Monkstown 14.8°C
15 Portmarnock 14.8°C
16 Portraine 14.8°C
17 Sandycove 14.8°C
18 Seapoint 14.8°C
19 Balbriggan 14.9°C
20 Bettystown 14.9°C
21 Carlingford 14.9°C
22 Dundalk 14.9°C
23 Laytown 14.9°C
24 Rush 14.9°C
25 Skerries 14.9°C
Show 25 more ▸
26 Bray 14.9°C
27 Dublin 14.9°C
28 Greystones 14.9°C
29 Drogheda 14.9°C
30 Bulbinbeg County Donegal 14.9°C
31 Malin Head County Donegal 14.9°C
32 Trawbreaga Bay County Donegal 14.9°C
33 Achill Island 14.9°C
34 Gweedore County Donegal 15.0°C
35 Inishbofin County Donegal 15.0°C
36 Tory Island County Donegal 15.0°C
37 Cranford Bay County Donegal 15.0°C
38 Fanad Head County Donegal 15.0°C
39 Rathmullan County Donegal 15.0°C
40 Dunfanaghy County Donegal 15.0°C
41 Mulroy Bay (Bar) County Donegal 15.0°C
42 Sheep Haven County Donegal 15.0°C
43 Enniscrone 15.1°C
44 Ballyglass (Broadhaven) County Mayo 15.1°C
45 Inishbiggle County Mayo 15.1°C
46 Inishbofin 15.1°C
47 An Ros County Dublin 15.1°C
48 Kish Bank County Dublin 15.1°C
49 River Boyne Entrance County Meath 15.1°C
50 Bundoran 15.1°C

Warmest 10 in Ireland in September

Same data the other way. The warmest spots for the same month.

# Location September mean
1 Ballycotton County Cork 16.1°C
2 Cork City County Cork 16.0°C
3 Crosshaven County Cork 16.0°C
4 Marino Point County Cork 16.0°C
5 Ringaskiddy County Cork 16.0°C
6 Roberts Cove County Cork 16.0°C
7 Courtmacsherry County Cork 15.9°C
8 Castletownshend County Cork 15.9°C
9 Clonakilty Bay County Cork 15.9°C
10 Ardmore 15.9°C

More on this region