Lake Llyn Gwynant — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Llyn Gwynant, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Llyn Gwynant today is 14.2°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 | 15.0°C | 19.0°C | |
| SEP 17 | 15.2°C | 19.0°C | |
| SEP 18 | 15.0°C | 19.0°C | |
| SEP 19 | 14.6°C | 19.0°C | |
| SEP 20 | 14.5°C | 19.0°C | |
| SEP 21 | 14.4°C | 19.0°C | |
| SEP 22 | 14.3°C | 19.0°C | |
| SEP 23 | 14.2°C | 19.0°C | |
| SEP 24 | 19.0°C | 14.4°C | |
| SEP 25 | 19.0°C | 14.7°C | |
| SEP 26 | 19.0°C | 14.9°C | |
| SEP 27 | 19.0°C | 15.2°C | |
| SEP 28 | 19.0°C | 15.4°C | |
| SEP 29 | 19.0°C | 15.6°C | |
| SEP 30 | 19.0°C | 15.9°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 | 10°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 Gwynant: Water Temperature by Location
Lake Llyn Gwynant: Weather Forecast
September 23
September 24
September 25
September 26
September 27
Location & Local Information
Llyn Gwynant is a natural lake in Snowdonia National Park, nestled in a picturesque valley beneath the slopes of Snowdon. Fed by clear mountain streams, the lake’s water remains cool for most of the year. In winter, temperatures often fall to around 3–5 °C (37–41 °F), while in spring they rise slowly to about 8–10 °C (46–50 °F). During summer, the surface water can reach 15–17 °C (59–63 °F) on calm, sunny days, though shaded or deeper parts stay several degrees cooler. By autumn, the lake cools again toward 9–11 °C (48–52 °F), reflecting the fresh, temperate conditions typical of upland North Wales.
Swimming in Llyn Gwynant is allowed and quite popular, especially during the warmer months. The water is clean and clear, and the gently shelving shoreline makes it suitable for both casual swimmers and more experienced open-water enthusiasts. Wetsuits are common outside midsummer, as the lake retains a mountain chill. Visitors often combine swimming with kayaking, paddleboarding, or picnicking along the scenic banks. The surrounding area offers stunning walks and viewpoints, including routes toward Snowdon, Llyn Dinas, and the Nant Gwynant Pass. The nearby village of Beddgelert and the waterfalls at Aberglaslyn Gorge make the lake a favourite spot for outdoor recreation in Snowdonia.