Lake Thirlmere — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lake Thirlmere, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lake Thirlmere today is 12.5°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 | 14.0°C | 19.0°C | |
| SEP 17 | 14.0°C | 19.0°C | |
| SEP 18 | 13.9°C | 19.0°C | |
| SEP 19 | 13.4°C | 19.0°C | |
| SEP 20 | 13.3°C | 19.0°C | |
| SEP 21 | 13.2°C | 19.0°C | |
| SEP 22 | 13.1°C | 19.0°C | |
| SEP 23 | 12.5°C | 19.0°C | |
| SEP 24 | 19.0°C | 12.8°C | |
| SEP 25 | 19.0°C | 13.2°C | |
| SEP 26 | 19.0°C | 13.5°C | |
| SEP 27 | 19.0°C | 13.8°C | |
| SEP 28 | 19.0°C | 14.1°C | |
| SEP 29 | 19.0°C | 14.5°C | |
| SEP 30 | 19.0°C | 14.8°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 | 1°C | 5°C | 8°C |
| February | 1°C | 5°C | 8°C |
| March | 3°C | 7°C | 10°C |
| April | 6°C | 10°C | 13°C |
| May | 9°C | 15°C | 21°C |
| June | 13°C | 20°C | 26°C |
| July | 15°C | 21°C | 27°C |
| August | 15°C | 21°C | 27°C |
| September | 13°C | 19°C | 24°C |
| October | 9°C | 13°C | 17°C |
| November | 4°C | 9°C | 12°C |
| December | 0°C | 4°C | 7°C |
Lake Thirlmere: Water Temperature by Location
Lake Thirlmere: Weather Forecast
September 23
September 24
September 25
September 26
September 27
Location & Local Information
#Cumbria
Thirlmere’s water remains cool year-round because it is a deep upland reservoir. Typical surface temperatures in summer range from about 12–18 °C (54–64 °F), occasionally reaching the upper end during calm late‑summer days. In spring and autumn the surface commonly sits between 5–11 °C (41–52 °F), while winter temperatures often fall to around 1–5 °C (34–41 °F), with ice possible in prolonged cold spells. Deeper water stays colder than the surface, so even warmer days can feel brisk.
Swimming in Thirlmere is generally discouraged rather than actively promoted. As a working reservoir it presents safety and water‑quality concerns: there are steep banks, submerged structures, variable depths, no lifeguards and a risk of cold‑water shock, so landowners and water companies advise against wild bathing. Visitors seeking open‑water swimming tend to use other nearby lakes and designated spots in the Lake District. The area does, however, offer plenty of low‑risk attractions, including popular walks around the reservoir, nearby fells such as Helvellyn, and villages like Grasmere and Keswick for hiking, cycling and sightseeing.