How cold is your water today?
Measured water temperatures for winter swimming across the UK, from 153 measuring points: sea, rivers and lakes. Not a forecast, real sensors in the water.
The coldest waters in the UK
The coldest of 153 measured points, one per water. Tap a water for its history and neighbours.
Your water on your phone, with an alert below your limit
BrrChecker shows 13,000+ measured spots with history and neighbours, alerts you when your water drops below your own threshold, and keeps your winter swimming diary with BrrLog: temperature, time in the water, streak.
From fresh to polar
Five bands every winter swimmer knows. The “one minute per degree” rule is for experienced swimmers, beginners stay well shorter.
Polar
Icy
Cold
Fresh
Summer
Well prepared for cold water
No health promises, just what experienced winter swimmers do. Check with a doctor first if you have heart or blood-pressure conditions.
Before
- Never go alone. Someone stays on the shore and watches.
- Check your exit first: shallow, non-slip, close.
- Lay out warm clothes, a hat and a flask in the order you will put them on.
- Sober and cold: no alcohol, no sauna sprint right before.
In
- Walk in slowly, head above water. No diving into cold water.
- Lengthen the first breaths on purpose, cold shock fades after one to two minutes.
- Rule of thumb for experienced swimmers: one minute per degree. Beginners stay well shorter.
- Get out before you shiver. Shivering is the signal, not the goal.
After
- Dry off and dress first, talk later. The body keeps cooling after you leave the water (afterdrop).
- Warm up from the inside: tea, movement, hat. No hot shower in the first minutes.
- Sit or walk for ten minutes before driving.
- Note water temperature and time, experience grows session by session.
When does it become ice swimming?
Example curve from multi-year measurements. Real values are on each water's linked page.
Frequently asked
At what temperature is it ice swimming?
Below 5 °C. Between 5 and 10 °C it is winter swimming, above that cold-water swimming. The limits are convention, the effect on the body is gradual.
How long can I stay in cold water?
A rule of thumb for experienced swimmers is one minute per degree of water temperature. Beginners stay well shorter and get out before shivering starts.
Where do the temperatures come from?
From public monitoring networks such as the Environment Agency, Cefas and coastal observatories, with sensors in the water. No model values, no forecast.
Which lidos are open in winter?
Several lidos and tidal pools are open year-round, for example Tooting Bec, Brockwell and Parliament Hill. The linked water pages show the measured temperature, opening hours are with the operators.