Clywedog Reservoir — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Clywedog Reservoir, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Clywedog Reservoir today is 12.1°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 |
|---|---|---|---|
| JUN 3 | 12.5°C | 18.8°C | |
| JUN 4 | 12.5°C | 18.8°C | |
| JUN 5 | 12.5°C | 18.8°C | |
| JUN 6 | 12.5°C | 18.8°C | |
| JUN 7 | 12.1°C | 18.8°C | |
| JUN 8 | 12.1°C | 18.8°C | |
| JUN 10 | 12.1°C | 18.8°C | |
| JUN 11 | 18.8°C | 12.4°C | |
| JUN 12 | 18.8°C | 12.8°C | |
| JUN 13 | 18.8°C | 13.1°C | |
| JUN 14 | 18.8°C | 13.4°C | |
| JUN 15 | 18.8°C | 13.8°C | |
| JUN 16 | 18.8°C | 14.1°C | |
| JUN 17 | 18.8°C | 14.4°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 | 0°C | 3°C | 6°C |
| February | 0°C | 4°C | 7°C |
| March | 2°C | 6°C | 9°C |
| April | 6°C | 10°C | 13°C |
| May | 9°C | 16°C | 22°C |
| June | 12°C | 19°C | 25°C |
| July | 16°C | 21°C | 26°C |
| August | 16°C | 21°C | 26°C |
| September | 11°C | 17°C | 22°C |
| October | 8°C | 12°C | 15°C |
| November | 3°C | 7°C | 10°C |
| December | 0°C | 4°C | 7°C |
Clywedog Reservoir: Water Temperature by Location
Clywedog Reservoir: Weather Forecast
June 9
June 10
June 11
June 12
June 13
Location & Local Information
Clywedog Reservoir lies in the upper Severn Valley near Llanidloes in mid-Wales, surrounded by rolling hills and forested slopes. Its altitude and size keep the water cool throughout the year, even during the summer months. In winter, the surface temperature typically falls to around 3–5 °C (37–41 °F), slowly rising to about 8–10 °C (46–50 °F) in spring. During July and August, the reservoir can reach 14–16 °C (57–61 °F) on sunny days, though deeper sections remain significantly colder. By autumn, the water cools again toward 9–11 °C (48–52 °F), following the steady seasonal rhythm typical of upland Welsh lakes. These conditions give the reservoir a fresh and invigorating feel, appealing to visitors who enjoy the outdoors.
Swimming in Clywedog Reservoir is allowed in designated areas but should be approached with care, as the water can be deep and unexpectedly cold even in summer. Wetsuits are recommended for open-water swimmers, and local clubs sometimes organize supervised events. The lake is better known for sailing, kayaking, and trout fishing, with excellent facilities along the shoreline. Surrounding walking trails offer panoramic views across the valley, and nearby attractions include Hafren Forest, the source of the River Severn, and the historic market town of Llanidloes.