Lough Derg — Current Water Temperature, Annual Trends and Forecast
This page provides information on the current water temperature in Lough Derg, trends, monthly ranges and the forecast for the coming days.
Current Water Temperature
Water Temperature in Lough Derg today is 18.8°C.
Water Temperature: Daily Trends, Historical Records, and Forecast
⚠️ As of today, the minimum water temperature ranges from 65°F (18°C) to 68°F (20°C). This is already quite warm water, which is ideal for most people. Swimming becomes comfortable, and prolonged stays in the water do not cause discomfort. This temperature is perfect for family trips and for those who prefer warmer water. It is also comfortable for water sports such as surfing or swimming. 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 |
|---|---|---|---|
| AUG 6 | 18.7°C | 22.0°C | |
| AUG 7 | 18.7°C | 22.0°C | |
| AUG 8 | 18.5°C | 22.0°C | |
| AUG 9 | 18.2°C | 22.0°C | |
| AUG 10 | 18.8°C | 22.0°C | |
| AUG 11 | 19.0°C | 22.0°C | |
| AUG 12 | 18.7°C | 22.0°C | |
| AUG 13 | 18.8°C | 22.0°C | |
| AUG 14 | 22.0°C | 19.0°C | |
| AUG 15 | 22.0°C | 19.1°C | |
| AUG 16 | 22.0°C | 19.3°C | |
| AUG 17 | 22.0°C | 19.4°C | |
| AUG 18 | 22.0°C | 19.6°C | |
| AUG 19 | 22.0°C | 19.8°C | |
| AUG 20 | 22.0°C | 19.9°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 | 0°C | 4°C | 8°C |
| February | 1°C | 5°C | 10°C |
| March | 3°C | 7°C | 10°C |
| April | 7°C | 11°C | 14°C |
| May | 10°C | 17°C | 23°C |
| June | 14°C | 20°C | 26°C |
| July | 16°C | 22°C | 27°C |
| August | 17°C | 22°C | 27°C |
| September | 12°C | 18°C | 23°C |
| October | 9°C | 13°C | 17°C |
| November | 4°C | 8°C | 13°C |
| December | 4°C | 7°C | 10°C |
Lough Derg: Water Temperature by Location
Lough Derg: Weather Forecast
August 14
August 15
August 16
August 17
Location & Local Information
Lough Derg, one of Ireland's largest lakes, offers a freshwater experience where water temperatures fluctuate significantly throughout the year. During the winter and early spring months, the water can be quite cold, typically ranging from about 6∘C to 10∘C (43∘F to 50∘F). As the summer progresses, the surface water warms considerably, peaking in the range of approximately 14∘C to 17∘C (57∘F to 63∘F), though deeper sections may remain cooler.
Swimming is actively encouraged and widely available, with the lake being a popular destination for water sports. Crucially, Lough Derg features multiple designated bathing areas, including Blue Flag beaches at Mountshannon, Ballycuggeran, and Portumna. These spots are officially recognised for their high water quality and safety, often offering lifeguard services during the peak summer bathing season, allowing visitors to swim freely and safely. Beyond swimming, the area boasts attractions like the historic monastic settlement on Holy Island (Inis Cealtra) and the picturesque towns of Killaloe and Ballina, which act as gateways to the lake and the wider Shannon region.