Lake Llyn Cwm Llwch — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Llyn Cwm Llwch, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Llyn Cwm Llwch today is 13.6°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 54°F (12°C) to 60°F (15°C). The water is significantly warmer, and swimming becomes possible for most people. However, caution may still be required for prolonged stays in the water, as extended exposure can cause discomfort. This is a suitable temperature range for short swims and for those accustomed to cooler water. For more comfortable swimming, it is recommended to use proper gear. 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.
Water Temperature Chart Over the Last 30 Days
Table of Daily Sea Temperature Data
| Date | Current | Average | Forecast |
|---|---|---|---|
| SEP 16 | 14.9°C | 19.0°C | |
| SEP 17 | 14.8°C | 19.0°C | |
| SEP 18 | 14.7°C | 19.0°C | |
| SEP 19 | 13.8°C | 19.0°C | |
| SEP 20 | 13.8°C | 19.0°C | |
| SEP 21 | 14.2°C | 19.0°C | |
| SEP 22 | 14.0°C | 19.0°C | |
| SEP 23 | 13.6°C | 19.0°C | |
| SEP 24 | 19.0°C | 13.9°C | |
| SEP 25 | 19.0°C | 14.1°C | |
| SEP 26 | 19.0°C | 14.4°C | |
| SEP 27 | 19.0°C | 14.7°C | |
| SEP 28 | 19.0°C | 15.0°C | |
| SEP 29 | 19.0°C | 15.2°C | |
| SEP 30 | 19.0°C | 15.5°C |
* Current - Actual water temperature value
** Average - Average water temperature on this day in recent years
*** Forecast - Our water temperature forecast
Actual nearshore water temperatures may fluctuate by several degrees from the reported values, especially following heavy rainfall or extended periods of strong winds. Certain wind patterns can cause colder, deeper waters to rise and replace the sun-warmed surface water, leading to noticeable variations.
Our forecast is based on a proprietary mathematical model that considers real-time water temperature changes, historical trends, key weather patterns, wind strength and direction, and air temperature specific to each region. Additionally, we incorporate data from other resorts to enhance accuracy.
Monthly Water Temperature Range (Min, Max & Average)
| Month | Min | Avg | Max |
|---|---|---|---|
| January | 1°C | 5°C | 8°C |
| February | 2°C | 6°C | 9°C |
| March | 4°C | 8°C | 11°C |
| April | 5°C | 10°C | 14°C |
| May | 7°C | 14°C | 20°C |
| June | 9°C | 18°C | 26°C |
| July | 11°C | 20°C | 27°C |
| August | 15°C | 21°C | 26°C |
| September | 13°C | 19°C | 24°C |
| October | 9°C | 13°C | 17°C |
| November | 3°C | 8°C | 11°C |
| December | 2°C | 6°C | 9°C |
Lake Llyn Cwm Llwch: Water Temperature by Location
Lake Llyn Cwm Llwch: Weather Forecast
September 23
September 24
September 25
September 26
September 27
Location & Local Information
Llyn Cwm Llwch is a small glacial lake high in the Brecon Beacons, sitting below the northern slopes of Pen y Fan, the highest peak in southern Wales. Because of its altitude and exposure to mountain weather, the water remains cold throughout the year. In winter, the temperature often drops to around 2–4 °C (36–39 °F), and it may partially freeze during cold spells. In spring, it rises slightly to about 6–8 °C (43–46 °F) as the snow melts from surrounding ridges. During summer, the lake can reach 12–14 °C (54–57 °F) on warm, still days, though it rarely feels mild. By autumn, temperatures fall again to near 8–10 °C (46–50 °F), keeping the water consistently refreshing and clear.
Swimming in Llyn Cwm Llwch is allowed but suited only to experienced wild swimmers due to its cold temperatures, sudden depth changes, and remote location. The water is pure and free of pollution, making it inviting for short dips in calm weather, especially after a hike up Pen y Fan. Wetsuits are recommended for comfort and safety. The lake’s dramatic mountain setting offers one of the most scenic natural swims in Wales. Nearby attractions include the hiking trails of the Brecon Beacons, Storey Arms Outdoor Centre, and panoramic viewpoints over the Usk Valley.