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Stillwaterwater reference

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The twelve-month temperature dashboard

21 spots · 2026-10-18

Cold, clear water, measured properly.

Twelve-month water temperature dashboard Each bar is the mean surface temperature across every published spot for that month; the pale band behind it is the min–max range. 0° 8° 16° 24° 32° January: mean 5.6 °C · 2–13.5 °C 5.6 J Jan February: mean 5.6 °C · 2–12.5 °C 5.6 F Feb March: mean 7.1 °C · 3–13 °C 7.1 M Mar April: mean 10 °C · 5.5–16.5 °C 10 A Apr May: mean 13.7 °C · 9–20 °C 13.7 M May June: mean 17 °C · 12.5–23.5 °C 17 J Jun July: mean 19 °C · 14.5–26.5 °C 19 J Jul August: mean 19.1 °C · 14.5–27 °C 19.1 A Aug September: mean 17 °C · 12–24.5 °C 17 S Sep October: mean 13.6 °C · 9–20 °C 13.6 O Oct November: mean 9.9 °C · 5.5–17.5 °C 9.9 N Nov December: mean 7.1 °C · 3–15 °C 7.1 D Dec

Solid bar — mean surface temperature across every published spot Pale band — coldest to warmest Coral — the current month Hover any bar for that month's figures

Every documented spot, by water type

Typing filters the list instantly. Every entry here is a text record — this page deliberately carries no scenic photography.

River

7

Flowing water. Depth changes without warning, levels respond to rain within hours, and the current is a factor in every swim.

River Wye at Symonds Yat Herefordshire / Gloucestershire border, England · 3.5 m · 3 min 12.5 °C October Upper Rhine at Rheinau Schaffhausen, Switzerland · 6.5 m · 5 min 13 °C October River Wharfe at Grassington Yorkshire Dales, England · 3 m · 8 min 11.5 °C October Berounka at Branov Central Bohemia, Czechia · 2.2 m · 2 min 12 °C October Verzasca at Lavertezzo Ticino, Switzerland · 8 m · 3 min 11 °C October Soča at Bovec Julian Alps, Slovenia · 3.2 m · 12 min 9.5 °C October River Dart at Newbridge Devon, England · 2.6 m · 4 min 12.5 °C October

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Lake

8

Still water with a summer thermocline. The warm surface layer is thin — cross it and the temperature falls sharply.

Lake Bled, Velika Zaka Gorenjska, Slovenia · 29.5 m · 3 min 15.5 °C October Fuxian Lake, Luchong shore Yunnan, China · 155 m · 4 min 19 °C October Qiandao Lake, Laoshan Bay Zhejiang, China · 100 m · 5 min 20 °C October Llyn Idwal Snowdonia (Eryri), Wales · 12 m · 25 min 9 °C October Lac d'Annecy, Plage de la Brune Haute-Savoie, France · 65 m · 2 min 14.5 °C October Buttermere Lake District, England · 23 m · 6 min 11 °C October Loch Morlich Cairngorms, Scotland · 12 m · 3 min 10 °C October Walchensee, Urfeld shore Bavaria, Germany · 190 m · 4 min 13 °C October

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Sea

3

Salt water, tidal range and swell. Temperature lags the seasons by six to eight weeks, peaking in late August.

Pomena, Mljet Dalmatia, Croatia · 22 m · 1 min 20 °C October The Forty Foot, Sandycove County Dublin, Ireland · 6 m · 8 min 14 °C October Bude Sea Pool Cornwall, England · 3.4 m · 5 min 14.5 °C October

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Lido & pool

3

Managed outdoor water. No current and no swell, but the unheated ones swing as widely as any river.

Bains des Pâquis, Geneva Geneva, Switzerland · 6 m · 4 min 16 °C October Tooting Bec Lido London, England · 2 m · 5 min 13 °C October Hampstead Heath Mixed Pond London, England · 3 m · 10 min 13.5 °C October

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Two other ways in

Browse by season Which spots suit which month of the year, with the pooled annual envelope figure. Where the numbers come from How monthly means are built, how heated pools are treated, and what a water-quality rating does and does not mean.

Stillwater

Stillwater is a reference for wild swimmers and open-water dippers: 28 documented swim spots across four water types, each with a twelve-month water temperature profile, an entry and exit route, and the safety notes that actually apply there. We do not write about swimming in the abstract. Every spot here has a named gauge, a named car park and a temperature curve built from published monitoring data.

Stillwater 是给野外泳者与开放水域泡水者的资料库：28 个已记录的泳点，分属四种水体类型，每处都附十二个月水温曲线、入水与上岸路线，以及真正适用于该地的安全须知。我们不写抽象的游泳文章。这里的每个泳点都有明确的水文站、明确的停车场，以及依据公开监测数据绘制的温度曲线。

Before you get in

Cold water is the one hazard that applies everywhere in this library. Below 15 °C the gasp reflex can make you inhale water involuntarily within seconds of immersion; below 10 °C, unacclimatised swimmers lose the ability to swim effectively within minutes. Enter gradually, keep your first session under five minutes, never swim alone, and get out while you still feel fine — the afterdrop continues after you leave the water.