UK Sea Temperature
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Live forecasts update automatically; written guidance last reviewed 14 June 2026 by the Pressorbit weather desk. Data from national met services via Open-Meteo.
Live data from Open-Meteo · updates automatically ·
UK sea temperatures range from a winter low of around 5°C in the North Sea to a summer peak of 17–19°C off the south-west coast. The water is rarely warm enough for prolonged swimming without thermal protection, but the live forecast above gives the current reading at your nearest coastal station.
What is the typical range of UK sea temperatures?
The sea around Britain is strongly seasonal. Winter averages (January–March) sit between 5°C and 9°C, with the coldest water in the North Sea and the warmest in the Western Approaches. By August, coastal waters reach their peak: 16–19°C in the English Channel and 17–19°C off Cornwall, while the North Sea temperature UK today still lags at 14–16°C. The highest sea temperature recorded in UK waters is about 22°C in shallow estuaries during prolonged summer heatwaves.
UK sea temperature by month
Monthly averages shift by about 1–2°C per month in spring and autumn. February is the coldest month nationally (6°C mean), August the warmest (17°C mean). The south-west coast sees the smallest seasonal variation; the east coast and northern Scotland see the largest. For a detailed breakdown, a sea temperature UK map from the Met Office shows regional gradients, but the live widget above gives the most current local reading.
River water temperature UK today – how does it compare?
While this guide focuses on the sea, river water temperature UK today is often several degrees colder than coastal sea temperature, especially in spring when rivers run with snowmelt or upland runoff. In summer, shallow rivers can warm more quickly than the sea, but fast-flowing sections remain below 15°C. The cold-water shock risk is higher in rivers because of the sudden contrast with air temperature.
North Sea temperature UK today and cold-water shock
The North Sea temperature UK today is typically the coldest of Britain’s coastal waters, averaging 5–8°C in winter and 14–16°C in late summer. Water below 15°C can trigger cold-water shock – a gasp reflex that can lead to drowning. The RNLI advises entering gradually, wearing a wetsuit, and checking the live forecast above before any open-water swim. See our UK weather warnings for storm surge alerts that affect coastal safety.
What wetsuit thickness do you need?
For water temperatures below 12°C (November–May) a 5/4mm wetsuit with hood, boots and gloves is recommended. In the 12–16°C range (June and October) a 3/2mm suit suffices for most. Above 16°C (July–September in the south) a shorty or rash vest may be enough for short dips, but the highest sea temperature UK rarely exceeds 19°C, so even summer swimmers often wear a thin wetsuit for comfort. Always cross-check the live conditions above with your local forecast.
Frequently asked questions about UK sea temperature
What is the highest sea temperature ever recorded in the UK?
The highest reliably recorded UK sea temperature is around 22°C in the shallow waters of the Solent and Poole Harbour during the summer of 2022. Open coastal waters rarely exceed 20°C. Temperatures above 21°C are exceptional and usually coincide with prolonged settled weather and high air temperatures.
How cold does the North Sea get in winter?
In winter (January–March), the North Sea temperature UK today can drop to 5°C off the Norfolk and Yorkshire coasts, and as low as 4°C in the deepest parts of the northern basin. This is cold enough to cause hypothermia within minutes without appropriate wetsuit protection. Check the live forecast above before any winter sea entry.
Is it safe to swim in UK seas in April?
April water temperatures average 8–11°C across the UK, with the south-west reaching 10–12°C. These temperatures pose a moderate cold-shock risk. Swimming is safe for experienced cold-water swimmers wearing a 5/4mm wetsuit, but beginners should limit exposure to a few minutes. Always consult the live sea temperature above and review our UK weather hub for local conditions.
For detailed coastal forecasts, see our Cornwall weather and Exeter weather pages, or check the 10-day forecast for your area. The live sea temperature widget above updates from Met Office buoys and coastal stations, giving you the most accurate reading for your chosen stretch of coast.
