Lake · Ireland
Lough Derg
Lake on River Shannon, in counties Clare (south-west), Galway (north-west), and Tipperary (to the east)
- Area
- 114km²
- Max depth
- 8m
- Average depth
- 15m
- Elevation
- 29m a.s.l.
- Shoreline
- 184km
- Volume
- 1.8km³
Lough Derg is a lake in Ireland. It covers 114 km². On average it is 15 m deep, and 8 m at its deepest point. Its surface lies 29 m above sea level.
Plan your visit
Stay, sail and get there
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The water
How warm is Lough Derg?
The water is warmest in July, around 17 °C at the surface, and coldest in January, around 4 °C. It rarely averages 20 °C, but it stays above 17 °C from July to August: brisk, refreshing swimming.
It does not normally freeze in winter.
On the shore, afternoons reach 19 °C on average in July and 7 °C in January. The driest month is April (67 mm of rain), the wettest November (111 mm).
Average surface temperature measured by the Landsat 8 satellite between 2013 and 2021 at the point furthest from the shore (54 readings). Shallow bays and beaches are often warmer.
From above
The whole lake from space
Month by month
The year at the lake, month by month
Not a forecast: these are averages over many years. Water is the 2013–2021 average; air, rain, sun and wind are the 1991–2020 average.
Water: 2013–2021 averageClimate: 1991–2020 average
| Month | Water°C | Water high°C | Air high°C | Air low°C | Rainmm | Rainy daysdays | Sunh/day | Windkm/h |
|---|---|---|---|---|---|---|---|---|
| January | 4 | 4 | 7 | 2 | 98 | 18 | 1.4 | 22 |
| February | 4 | 5 | 8 | 2 | 77 | 15 | 2.6 | 21 |
| March | 6 | 8 | 9 | 2 | 75 | 16 | 4.1 | 20 |
| April | 9 | 11 | 12 | 4 | 67 | 14 | 6.0 | 18 |
| May | 13 | 14 | 15 | 7 | 76 | 15 | 6.5 | 18 |
| June | 16 | 17 | 18 | 10 | 86 | 16 | 6.1 | 17 |
| July | 17 | 18 | 19 | 11 | 93 | 19 | 4.9 | 17 |
| August | 17 | 18 | 18 | 11 | 100 | 18 | 4.6 | 17 |
| September | 15 | 16 | 17 | 9 | 81 | 15 | 4.2 | 18 |
| October | 12 | 14 | 13 | 7 | 100 | 17 | 3.1 | 19 |
| November | 8 | 10 | 10 | 5 | 111 | 18 | 1.7 | 20 |
| December | 5 | 6 | 8 | 3 | 105 | 18 | 1.0 | 21 |
Water: LakeTEMP (Landsat 8, 2013–2021). Air, rain, sun and wind: NASA POWER, 1991–2020 averages. A rainy day has at least 1 mm of rain. Sunshine hours are derived from measured solar radiation.
Size & depth
How big, how deep
- On average, water stays in the lake for about 3 months before flowing out.
- Its catchment drains 10,734 km² of land.
- About 191 m³ of water flow out every second, on average.
- Its shoreline is 4.9 times longer than a circle of the same area: plenty of bays and inlets.
Around the shore
What's around Lough Derg
Counted within 1.5 km of the shoreline in OpenStreetMap, the map anyone can edit.
- 2beaches and swimming spots
- 5campsites
5th/22nd Killaloe Scout Group, Lakeside Holiday Park, Killaloe Camping
- 2boat hire and water-sport clubs
Shannon Castle Line
- 43marinas and slipways
University of Limerick Activity Centre, Kilgarvan Quay, Rossmore Quay, Rossmore, Castle Harbour and 38 more
- —ferry piers
- 2viewpoints
- 17hotels, B&Bs and chalets
Lakeside Hotel, Lakeland House, Ballyheefy Lodge, Canter's Lodge, Carramore Lodge and 12 more
- —fishing spots
- 23restaurants and cafés
Towns on the shore
- Ballina2,442 people
- Killaloe1,484 people
- Portumna1,450 people
Nearest airport with scheduled flights: Shannon Airport (SNN), 52 km in a straight line.
Car hire at SNN airport (Shannon)Discover Cars · Affiliate linkOpenStreetMap is built by volunteers: when a number is low, it may just mean nobody has mapped it yet.
Recent years
How each month compared
Afternoon high on the shore. The first row is the reference, the 1991–2020 average in °C; the years below show the difference from it: warmer in orange, cooler in blue.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1991–2020 average | 7.1 | 7.5 | 9.2 | 12.2 | 15.0 | 17.8 | 19.0 | 18.5 | 16.7 | 13.2 | 9.6 | 7.5 |
| 2020 | +0.5 | +0.2 | −0.1 | +1.6 | +1.5 | −0.6 | −0.9 | +0.9 | +0.1 | −1.3 | +0.7 | −0.5 |
| 2021 | −1.3 | +0.3 | +1.1 | −0.6 | −1.4 | +0.5 | +2.5 | +0.7 | +1.7 | +1.0 | +0.5 | +1.2 |
| 2022 | +0.8 | +1.6 | +1.6 | +0.6 | +1.0 | −0.3 | +1.9 | +2.2 | +0.3 | +1.5 | +1.0 | −1.7 |
| 2023 | +0.4 | +1.7 | ±0.0 | +0.3 | +2.2 | +2.8 | −0.8 | +0.5 | +1.7 | +0.6 | −0.2 | +1.1 |
| 2024 | −0.7 | +1.9 | +0.6 | +0.1 | +1.8 | −0.4 | −0.5 | +0.2 | −0.2 | +0.7 | +0.9 | +1.3 |
| 2025 | −0.5 | +0.9 | +1.9 | +2.3 | +2.9 | +1.1 | +1.4 | +1.6 | −0.6 | +0.3 | +0.7 | +0.5 |
+1 warmer than usual −1 cooler than usual
About these numbers
| Outline, area, depth, volume | HydroLAKES v1.0 (Messager et al. 2016) · CC BY 4.0 |
|---|---|
| Water temperature and ice | LakeTEMP v1 (Korver et al. 2024), Landsat 8 2013–2021 · CC BY 4.0 |
| Air, rain, sun, wind | NASA POWER, 1991–2020 · public domain |
| Names and description | Wikidata (Q918349) · CC0 |
| Around the shore | © OpenStreetMap contributors · ODbL |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
Every figure is an average or a count from a public dataset. Licences and methods: data sources.
