Lake Llyn Alaw — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Llyn Alaw, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Llyn Alaw today is 14.1°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 |
|---|---|---|---|
| SEP 16 | 15.3°C | 19.0°C | |
| SEP 17 | 15.2°C | 19.0°C | |
| SEP 18 | 15.1°C | 19.0°C | |
| SEP 19 | 15.0°C | 19.0°C | |
| SEP 20 | 14.9°C | 19.0°C | |
| SEP 21 | 15.1°C | 19.0°C | |
| SEP 22 | 14.6°C | 19.0°C | |
| SEP 23 | 14.1°C | 19.0°C | |
| SEP 24 | 19.0°C | 14.3°C | |
| SEP 25 | 19.0°C | 14.6°C | |
| SEP 26 | 19.0°C | 14.8°C | |
| SEP 27 | 19.0°C | 15.1°C | |
| SEP 28 | 19.0°C | 15.3°C | |
| SEP 29 | 19.0°C | 15.6°C | |
| SEP 30 | 19.0°C | 15.8°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 | 2°C | 6°C | 9°C |
| February | 2°C | 6°C | 9°C |
| March | 3°C | 7°C | 10°C |
| April | 7°C | 11°C | 14°C |
| May | 11°C | 17°C | 22°C |
| June | 14°C | 21°C | 27°C |
| July | 17°C | 23°C | 28°C |
| August | 16°C | 22°C | 27°C |
| September | 13°C | 19°C | 24°C |
| October | 10°C | 14°C | 18°C |
| November | 5°C | 9°C | 12°C |
| December | 2°C | 6°C | 9°C |
Lake Llyn Alaw: Water Temperature by Location
Lake Llyn Alaw: Weather Forecast
September 23
September 24
September 25
September 26
September 27
Location & Local Information
Llyn Alaw is a man-made reservoir located in the north of Anglesey, surrounded by gentle farmland and open countryside. The lake’s exposed position and shallow depth mean that its water temperature changes noticeably with the seasons, though it rarely becomes warm. In winter, the surface temperature usually ranges between 4–6 °C (39–43 °F), gradually increasing to around 8–10 °C (46–50 °F) in spring. During the summer, the water can reach about 14–17 °C (57–63 °F) on sunny days, particularly near the edges, while breezy conditions often keep the open water cooler. By autumn, temperatures drop again toward 9–11 °C (48–52 °F), maintaining the fresh and clear quality typical of reservoirs in coastal Wales.
Swimming in Llyn Alaw is not officially encouraged, as it serves primarily as a water supply and recreational area for fishing and birdwatching. However, some experienced open-water swimmers have used it informally during calm summer periods, taking care to stay close to the shore and avoid restricted zones. The lake’s surroundings are peaceful and scenic, offering walking paths and picnic spots. Nearby attractions include the Anglesey Coastal Path, Parys Mountain, and the beaches of Cemaes Bay, which provide safer and more popular options for open-water swimming and coastal recreation.