Celtic Sea Water Temperature Today & Regional Overview
We find every place where you can swim and show you the water temperature there today and throughout the year.
Current Water Temperature
The water temperature in the Celtic Sea today ranges from 16°C (Plounéour-Trez, France) to 22.3°C (Chepstow, United Kingdom).
As of today, the minimum water temperature in the Celtic Sea ranges from 60°F (15°C) to 65°F (18°C). The water is comfortable for most people, making it an ideal range for water sports enthusiasts. The temperature does not cause significant discomfort, and swimming will be pleasant for the majority. However, it's important to remember that prolonged exposure to the water can still lead to cooling, so it's essential to monitor the time spent in the water, especially for children or elderly people.
It is important to note that these swimming tips and recommendations apply only in good weather. When the air temperature is below 68°F (20°C), and sometimes even below 77°F (25°C), swimming can be unpleasant even with relatively high water temperatures.
Sea Temperature Trends
Over the past month, the water temperature in the Celtic Sea has increased by 5°C. In general, the sea water temperature remains within the statistical range for this time of year.
Water Temperature and Swimming Conditions Throughout the Year
| Month | Min | Max |
|---|---|---|
| January | 4°C | 13°C |
| February | 4°C | 12°C |
| March | 5°C | 12°C |
| April | 6°C | 14°C |
| May | 8°C | 16°C |
| June | 9°C | 19°C |
| July | 11°C | 21°C |
| August | 13°C | 21°C |
| September | 13°C | 21°C |
| October | 11°C | 19°C |
| November | 9°C | 17°C |
| December | 6°C | 15°C |
The Celtic Sea, lying south of Ireland and west of southwestern Britain, experiences cool to mild sea surface temperatures influenced by Atlantic waters and the North Atlantic Drift. Seasonal ranges typically run from around 9 to 11 °C in winter (December to February), gradually warming through spring to roughly 10 to 13 °C (March to May). Summer months (June to August) bring the warmest conditions, with surface temperatures commonly between 14 and 18 °C and occasional local highs near 18 °C in sheltered inlets or during unusually warm years. Autumn (September to November) sees a gradual cooling, with temperatures usually in the 12 to 15 °C range as stored summer heat dissipates and Atlantic weather systems regain strength. Local variations occur: shallow bays and estuaries can be slightly warmer in summer, while open-ocean areas remain more consistent, and short-term weather can shift surface values by a few degrees.
Swimming Conditions
Swimming in the Celtic Sea is permitted and popular at many coastal beaches, especially during the summer when air and water temperatures are at their highest. However, even in summer the water remains relatively cool compared with more southerly seas, so many swimmers use wetsuits outside the warmest weeks. Strong tides, rip currents and changeable weather are common, so safety considerations are important; lifeguarded beaches operate seasonally and swimmers are advised to heed local guidance. For most people recreational swimming is feasible from late spring to early autumn with appropriate precautions, but cold-water exposure and local conditions determine individual comfort and safety.