Photo: Amakuru · CC BY-SA 4.0An estimated 5.1% of homes in Dún Laoghaire sit above the radon reference level
Steady ground does most for Dún Laoghaire’s grade: with 0% of homes on landslide-prone ground, it grades B, #58 of 116 in County Dublin. Flood counts only against a town, so its share of low-lying homes earns it no credit: radon and landslide ground set the grade.
What stands out about Dún Laoghaire’s hazards
From the EPA’s radon map, Geological Survey Ireland’s landslide map, the OPW’s flood relief schemes and our estimate of low-lying homes, below.
What Dún Laoghaire faces
Each hazard against its own yardstick; meters run from low to high on that yardstick.
Low-lying homes
By the coast
Radon
Landslides
Bathing water
Ground heights
Dún Laoghaire grades B for hazard risk
Radon, landslide ground and low-lying homes, each against Irish towns, then averaged.
Each figure is placed among Irish towns of 1,000 or more people; the grade averages the three, so a better place on each is a better grade.
Flood counts only against a town, never for it: Dún Laoghaire’s share of low-lying homes would have raised its grade, so it isn’t counted, and radon and landslide ground set it.
Its place: #58 of 116 in County Dublin and #127 of 321 Irish towns.
Less sure: The low-lying figure is our estimate from ground heights and the river map, not an official flood map. It can show a town is low-lying; it can’t show a town is safe.
Few of Dún Laoghaire’s homes stand low by a big river, lake or the sea
Low-lying homes, a TownRatings estimate from OPW and Geological Survey Ireland LiDAR ground heights and the EPA’s river map: not an official flood map. Smaller streams, drains and groundwater aren’t in this measure, so a low figure doesn’t mean a town never floods.
Share of each town’s homes standing low by big water, for the towns measured in detail. 43% have none; Dún Laoghaire has more than 48% of them.
| # | Town | People | Low-lying | |
|---|---|---|---|---|
| 1 | Crumlin Dublin | 19,287 | 0% | |
| 2 | Mulhuddart Dublin | 19,252 | 0% | |
| 3 | Esker Dublin | 19,110 | 0% | |
| … | ||||
| 20 | Clonskeagh Dublin | 14,142 | 0.2% | |
| 21 | Knocknacarra Galway | 18,398 | 0.2% | |
| 22 | Dún Laoghaire Dublin | 17,994 | 0.3% | |
| 23 | Carpenterstown Dublin | 20,967 | 0.5% | |
| 24 | Greystones-Delgany Wicklow | 22,009 | 0.6% | |
| … | ||||
| 39 | Corbally and King's Island Limerick | 14,213 | 48% | |
| 40 | East Wall Dublin | 15,907 | 100% | |
The 40 Irish towns nearest its size that are measured in detail.
Low-lying homes across County Dublin’s towns · 106 towns measured in detail
Dún Laoghaire ranks 32nd of County Dublin’s 106 towns measured in detail, counting from the most low-lying homes.
Homes: OpenStreetMap buildings of 30 m² or more, not tagged as non-residential, in the town’s Census 2022 Small Areas. Heights: GSI Open Topographic Data LiDAR (OPW, TII and GSI surveys). Water: EPA river network (rivers of Strahler order 5 or more), lakes, estuaries and coastal waters.
Weather and flood warnings for Dún Laoghaire
Where to see the warnings in force, and what this page can’t count.
Met Éireann issues yellow, orange and red warnings for rain, wind and coastal flooding county by county; Dún Laoghaire is covered by County Dublin’s.
| Warning | What Met Éireann means by it |
|---|---|
| Yellow | Weather that isn’t unusual but can be dangerous in places: be aware. |
| Orange | Infrequent, dangerous weather that can put people and property at risk: be prepared. |
| Red | Rare, extremely dangerous weather: take action to protect yourself and your property. |
Met Éireann doesn’t publish an open archive of past warnings, so how often warnings have covered Dún Laoghaire can’t be counted here.
No OPW flood relief scheme protects Dún Laoghaire
The Office of Public Works’ completed flood relief schemes and the areas each one benefits (OPW open data, CC BY 4.0).
None of the OPW’s completed flood relief schemes has a benefiting area that takes in Dún Laoghaire’s homes. The OPW builds schemes where the risk to homes is greatest, so most towns have none.
In County Dublin, OPW schemes protect parts of 12 other places, including Dublin, Clonsilla, Sandymount, Mulhuddart, East Wall.
| Town | Scheme | Designed for | Homes behind it | Away |
|---|---|---|---|---|
| Sandymount Dublin | River Dodder (Tidal) | 1 in 50 | 37% | 7.1 km |
| Ballsbridge Dublin | River Dodder (Tidal) | 1 in 50 | 32% | 8.5 km |
| Grand Canal Dock Dublin | South Campshires Flood Relief Scheme | 1 in 200 | 14% | 9.2 km |
| St Stephen's Green Dublin | South Campshires Flood Relief Scheme | 1 in 200 | 5.9% | 9.7 km |
| East Wall Dublin | Spencer Dock Flood Relief Scheme | 1 in 200 | 82% | 9.7 km |
| Bray Wicklow | Bray (River Dargle) Flood Relief Scheme | 1 in 100 | 5% | 10 km |
No home in Dún Laoghaire stands on landslide-prone ground
Geological Survey Ireland’s landslide susceptibility map (1:50,000), read at every home.
Homes on ground rated high or moderately high
Dún Laoghaire is among the 64% of Irish towns with no home on such ground.
GSI rates ground from low to high by its slope, soil and rock. Most Irish landslides are on steep upland slopes and peat after heavy rain; a town on flat ground has almost none.
High means the ground could slide under the right conditions, such as days of heavy rain on a steep, wet slope; it isn’t a forecast that it will.
GSI landslide susceptibility, high and moderately high classes, share of the town’s homes on mapped ground (CC BY 4.0).
An estimated 5.1% of Dún Laoghaire’s homes are above the radon reference level
The EPA’s radon map: for each 10 km square, the estimated share of homes above the national reference level of 200 Bq/m³.
A square where 10% or more of homes are estimated above the reference level is a High Radon Area; 0% of Dún Laoghaire’s homes are in one. The map is an estimate by area: two neighbouring houses can differ a lot.
A test is the only way to know a home’s level: two detectors, left for three months in a living room and a bedroom.
EPA radon map of Ireland (10 km grid), averaged over the town’s homes (CC BY 4.0).
2 EPA-licensed sites within 5 km of Dún Laoghaire’s centre, none inside it
Factories, farms, power plants and waste sites that hold an EPA licence for their emissions, in Dún Laoghaire and around its centre.
| Site | Licence and activity | Away |
|---|---|---|
| embecta Penel Limited | IPC licence | 2.0 km |
| Amgen Technology (Ireland) Unlimited Company | Industrial Emissions licence · chemicals | 2.0 km |
| Sleever International Limited | IPC licence | 5.5 km |
| Ballyogan Landfill Facility Ballyogan Recycling Park | Waste licence | 5.5 km |
| Sytheses Limited | Industrial Emissions licence | 5.7 km |
| Electricity Supply Board (Poolbeg) | Industrial Emissions licence · energy | 6.7 km |
| Dublin Waste to Energy Limited | Industrial Emissions licence · waste | 7.1 km |
| Ringsend FlexGen | Industrial Emissions licence · energy | 7.3 km |
| Activity | Sites |
|---|---|
| Not classed in the register | 9 |
| Waste | 9 |
| Energy | 4 |
| Chemicals | 1 |
Within 5 km: one under an Industrial Emissions licence and one under an older IPC licence.
An EPA licence sets what a site may release to air, water and land; it doesn’t mark the site as an accident hazard.
Sites holding dangerous substances in bulk come under the COMAH (Seveso) rules, but the HSA’s list of them has no open licence, so upper- and lower-tier sites aren’t counted here.
Source: EPA registers of Industrial Emissions, IPC and waste licences, sites licensed on 31 October 2026; distances in a straight line from the town’s centre.
Hazards in the places around Dún Laoghaire
Low-lying homes, radon and landslide ground, town by town.
| Town | Low-lying | Radon | Landslides |
|---|---|---|---|
| Dún Laoghaire | 0.3% | 5.1% | 0% |
| Sallynoggin 13,245 · 0.9 km | 0% | 5.1% | 0% |
| Monkstown 9,831 · 2.0 km | 0.6% | 5.1% | 0.3% |
| Dalkey 8,275 · 2.1 km | under 0.1% | 5.1% | 4.6% |
| Foxrock 12,163 · 3.1 km | 0% | 5.1% | 0.2% |
| Blackrock 12,816 · 3.2 km | under 0.1% | 5.1% | 0% |
| Ballybrack 2,872 · 3.2 km | 0% | 5.1% | 0% |
None of the measured places around Dún Laoghaire has many homes standing low by big water.
A dash under Low-lying: not measured there (too few homes with detailed ground heights), not none.
Get ready for what Dún Laoghaire faces
What to do, and what to ask before you move.
- Never walk or drive through floodwater: 30 cm of moving water can float a car.
- Move valuables, papers and medicines upstairs.
- Turn off gas, electricity and water if you’re told to.
- Test over three months, in a living room and a bedroom.
- Above 200 Bq/m³, a small sump and fan usually fixes it.
- The EPA sells radon test kits at radon.ie and lists registered contractors who fix high readings.
- Bring in or tie down bins, trampolines and anything the wind can lift.
- Keep away from coastal paths and piers while an orange or red warning is in force.
- Charge phones and keep a torch: fallen lines are the commonest storm damage.
- After the storm, report a fallen line to ESB Networks and keep well clear of it.
- Ask whether the home has ever flooded, and get a buildings insurance quote before you commit: flood cover isn’t always offered.
- Ask the seller or landlord for a radon test result, or test in your first months there.
- Check the address on floodinfo.ie: the OPW’s flood maps and its record of past floods.
What this data can and can’t tell you
- An estimate, not a flood map. Low-lying homes is a TownRatings modelling step: each home’s ground height from LiDAR, against the level of the nearest big river (Strahler order 5 or more), lake or estuary within 1 km, or the sea within 2 km. A home within 5 m of the water’s level, or below 4 m near the sea, counts.
- Flood counts only one way. A high share of low-lying homes lowers the Hazard risk Grade; a low share never raises it, because defences, small streams, culverts, groundwater and flash floods don’t show in ground heights. Below the national median a town scores as the median.
- Defences aren’t counted. Flood defences aren’t taken off: the OPW scheme that protects the most homes is shown instead, with its design standard.
- Measured where the heights are detailed. A town is measured, and counted, only where 80% of its homes stand on LiDAR heights. Elsewhere the page says flooding isn’t measured, never that the town is dry.
- Radon is an estimate by area. The EPA’s radon map gives the estimated share of homes above 200 Bq/m³ for each 10 km square, averaged here over the town’s homes. It says where to test, not what one house holds.
- The sea is measured by height. Homes count as low by the sea when their ground is under 4 m and within 2 km of coastal or estuary water; waves, surges and erosion aren’t modelled.
- Landslide ground is a map of where slides could start. GSI’s susceptibility map rates the ground itself; it doesn’t record past slides or say when one will happen.
- Bathing water is rated season by season. The EPA classes each identified bathing water from four seasons of samples; a rating says how clean the water has been, not how safe it is to swim.
- One town, many streets. Risk is street by street. Check a specific address on floodinfo.ie before you buy or rent.
Check any address against the OPW’s official flood maps on floodinfo.ie
Questions about flooding and hazards in Dún Laoghaire
Does Dún Laoghaire flood?
Smaller streams, drains and groundwater aren’t in that measure, so it doesn’t mean the town never floods. For a single address, the OPW’s official flood maps and past floods are on floodinfo.ie.
Is radon a problem in Dún Laoghaire?
The EPA’s map estimates that about 5.1% of homes around Dún Laoghaire are above the radon reference level of 200 Bq/m³: a higher share than in 56% of Irish towns. 0% of its homes are in a High Radon Area. The only way to know a house is a three-month test.
Is Dún Laoghaire at risk of landslides?
No home in Dún Laoghaire stands on ground rated high or moderately high for landslides.
Is Dún Laoghaire at risk from the sea?
About 0.3% of Dún Laoghaire’s homes stand below 4 m within 2 km of the sea, against 0% standing low by rivers, lakes and estuaries. Coastal floods come with storm surges and spring tides; the OPW’s coastal maps on floodinfo.ie show the official picture.
How does Dún Laoghaire compare with the places around it?
Radon estimates around Dún Laoghaire run from 5.1% in Sallynoggin to 5.1% in Ballybrack; Dún Laoghaire’s own is 5.1%.
Where is the nearest bathing water to Dún Laoghaire?
Sandycove Beach, 1.4 km away, was rated good for the 2025 season; 11 identified bathing waters lie within 15 km.
How is Dún Laoghaire’s Hazard risk Grade worked out?
Dún Laoghaire grades B: radon, landslide ground and low-lying homes are each placed among Irish towns, and the grade averages them.
Flood: TownRatings’ estimate from ground heights, not an official flood map. Contains Irish Public Sector Data (Geological Survey Ireland, the Office of Public Works and the EPA) licensed under CC BY 4.0; Copernicus DEM © DLR e.V. and © Airbus, provided under COPERNICUS by the EU and ESA; © OpenStreetMap contributors. Radon and bathing water: EPA (CC BY 4.0). Landslide susceptibility: Geological Survey Ireland (CC BY 4.0).
Sources: low-lying homes: TownRatings’ estimate from GSI and OPW LiDAR, Copernicus GLO-30 and the EPA river network · radon: EPA radon map · landslides: GSI landslide susceptibility · bathing water: EPA bathing water quality · industrial sites: EPA licence registers · the grade: TownRatings, from these figures. Under Creative Commons Attribution 4.0 (CC BY 4.0).
Contains Central Statistics Office (CSO) data, Census 2022, and Tailte Éireann boundaries (CSO Urban Areas, Small Areas, local electoral areas, constituencies), under Creative Commons Attribution 4.0 (CC BY 4.0).