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Weymouth harbour, Dorset, EnglandPhoto: ITookSomePhotos · CC BY-SA 4.0
C−Hazard risk Grade
Flood & hazards in Weymouth · Environment Agency

Surface water, more than the river, is Weymouth’s flood risk: 6.7% of homes, against 1.7% from rivers or the sea

On the Environment Agency’s maps, which allow for flood defences, “high or medium” means at least a 1 in 100 chance of flooding from rivers or the sea in any year. Hazard risk puts Weymouth at C−: #24 of 30 in Dorset.

128flood warnings since 200677%in a radon Affected Area
In brief

What stands out about Weymouth’s hazards

From the Environment Agency’s maps and records and the BGS radon atlas, below.

Rain, more than the river6.7% of homes sit where heavy rain can flood the streets, against 1.7% at risk from rivers and the sea.The River Wey ran its 5th-highest in January 20260.60 m at Broadwey on 27 January 2026, 15 cm under the record set in 1993.128 flood warnings since 2006For the parts of Weymouth the Environment Agency warns directly; the most recent on 18 February 2026.Radon in parts5% of the town is in 1 km squares where 5% or more of homes may be above the radon action level.
By hazard

What Weymouth faces

Each hazard against its own yardstick; meters run from low to high on that yardstick.

Rivers and the sea

1.7%of homes at high or medium risk
More than the typical UK town · more than 76% of towns
539 homes by the EA’s own count

Surface water

6.7%of homes at high or medium risk
More than 82% of UK towns
Rivers and sea: 1.7%

The River Wey

0.60 mhighest in winter 2025–26 at Broadwey
5th-highest of 36 winters
Record 0.75 m, December 1993

Flood warnings

128flood warnings since 2006
512 flood alerts for the wider area
Last warning 18 February 2026

Radon

77%of the town in a radon Affected Area
Highest band here: Over 30% of homes
5% in squares of 5% or more
Not on this page: coastal erosion, subsidence and shrink-swell ground (the British Geological Survey licenses it), groundwater flooding and reservoir failure.
Hazard risk Grade

Weymouth grades C− for hazard risk

Flood risk from rivers and the sea, against all UK towns.

Homes at high or medium flood risk (1.7%)Fewer than 24% of UK towns

The share of homes at high or medium risk from rivers and the sea, ranked against every UK town of 1,000 or more: fewer homes at risk is better. Towns with none at high or medium risk are ordered by their share at low risk, so they don’t all share one score. Surface water and radon aren’t graded: they are described below.

Flood map

Where the water goes in Weymouth

Turn layers on and off. Blue is the risk from rivers and the sea; pink is where heavy rain collects. Both allow for flood defences.

© OpenStreetMap contributors · EA NaFRA2
HighMediumLowrivers & seaHighMediumLowsurface waterWeymouth’s built-up area

The river and sea risk follows the English Channel, the Portland Harbour and the Groundwater. Surface-water risk is spread across the town, in dips, underpasses and along small streams, which is why more homes are exposed to it.

Rivers and the sea

1.7% of Weymouth’s homes are at high or medium risk from rivers or the sea

The Environment Agency’s national map, allowing for defences. A further 1.8% are at low risk.

High risk1%of homes · 1 in 30 a year or more284 homes, EA count
Medium risk0.8%of homes · 1 in 30 to 1 in 100255 homes, EA count
Low risk1.8%of homes · 1 in 100 to 1 in 1,000513 homes, EA count
Where Weymouth sits among 3,735 UK towns
35%None
23%Under 0.5%
9%0.5–1%
11%1–2%Weymouth
11%2–5%
5%5–10%
3%10–20%
2%20% +

Share of each UK town’s homes at high or medium risk from rivers and the sea. 35% of UK towns have none; Weymouth has more than 76% of towns.

Towns its size: 109th of 134 from the fewest homes at risk
#TownPeopleHigh or med.
1Dudley West Midlands64,2770%
2Smethwick West Midlands56,3430%
3Bootle Merseyside53,7220%
…
107Keighley West Yorkshire48,7541.6%
108Oldbury West Midlands45,1881.7%
109Weymouth Dorset55,5401.7%
110Carlisle Cumbria77,7291.8%
111Cheshunt Hertfordshire43,6941.8%
…
133Neath West Glamorgan40,7387.2%
134West Molesey Surrey47,1447.2%

UK towns of 39,000 to 78,000 people.

The Environment Agency’s Risk of Flooding from Rivers and Sea (NaFRA2, June 2026) counts each postcode’s homes by band; the shares weight those postcodes by Census 2021 households. The EA counts include homes built since 2021.

Surface water

Heavy rain puts about 3.9 times as many Weymouth homes at risk as rivers and the sea do

Surface water is rain that falls faster than drains and the ground can take it. It is mapped separately from rivers and the sea, and it is not in the Hazard risk Grade.

Surface water6.7%
Rivers and the sea1.7%
0%7%14% of homes

About 3.6% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 3.2% at medium risk: roughly 1,740 households. A further 6% face a low risk from surface water. That is more than 82% of UK towns.

~1,740
households at high or medium risk
6%
of homes at low risk
82%
of UK towns have a smaller share
34,423
addresses read on the map

Our estimate: every address in the town (ONS NSUL) read on the Environment Agency’s Risk of Flooding from Surface Water map (NaFRA2, 2025), each postcode’s share weighted by its Census 2021 households. Neither agency publishes a count of homes for surface water, so treat it as a guide; one street can differ from the next.

River levels

The River Wey in January 2026 rose to its 5th-highest level since 1990

The highest level each winter (October to September) at the Environment Agency’s Broadwey gauge, since 1990. The river normally runs between 0.13 m and 0.35 m here.

Highest level each winter, metres
Winter 1990–91: highest 0.29 m · 0 days above the normal rangeWinter 1991–92: highest 0.23 m · 0 days above the normal rangeWinter 1992–93: highest 0.41 m · 1 days above the normal rangeWinter 1993–94: highest 0.75 m on 30 December 1993 · 41 days above the normal rangeWinter 1994–95: highest 0.44 m · 39 days above the normal rangeWinter 1995–96: highest 0.33 m · 0 days above the normal rangeWinter 1996–97: highest 0.26 m · 0 days above the normal rangeWinter 1997–98: highest 0.44 m · 19 days above the normal rangeWinter 1998–99: highest 0.38 m · 3 days above the normal rangeWinter 1999–00: highest 0.72 m on 24 December 1999 · 3 days above the normal rangeWinter 2000–01: highest 0.57 m · 35 days above the normal rangeWinter 2001–02: highest 0.39 m · 1 days above the normal rangeWinter 2002–03: highest 0.58 m on 1 January 2003 · 66 days above the normal rangeWinter 2003–04: highest 0.43 m · 2 days above the normal rangeWinter 2004–05: highest 0.26 m · 0 days above the normal rangeWinter 2005–06: highest 0.46 m · 1 days above the normal rangeWinter 2006–07: highest 0.39 m · 5 days above the normal rangeWinter 2007–08: highest 0.43 m · 2 days above the normal rangeWinter 2008–09: highest 0.53 m · 5 days above the normal rangeWinter 2009–10: highest 0.51 m · 2 days above the normal rangeWinter 2010–11: highest 0.31 m · 0 days above the normal rangeWinter 2011–12: highest 0.69 m on 7 July 2012 · 18 days above the normal rangeWinter 2012–13: highest 0.61 m on 22 December 2012 · 98 days above the normal rangeWinter 2013–14: highest 0.51 m · 69 days above the normal rangeWinter 2014–15: highest 0.33 m · 0 days above the normal rangeWinter 2015–16: highest 0.51 m · 18 days above the normal rangeWinter 2016–17: highest 0.36 m · 1 days above the normal rangeWinter 2017–18: highest 0.45 m · 10 days above the normal rangeWinter 2018–19: highest 0.34 m · 0 days above the normal rangeWinter 2019–20: highest 0.56 m · 67 days above the normal rangeWinter 2020–21: highest 0.48 m · 23 days above the normal rangeWinter 2021–22: highest 0.35 m · 1 days above the normal rangeWinter 2022–23: highest 0.46 m · 7 days above the normal rangeWinter 2023–24: highest 0.59 m on 4 November 2023 · 78 days above the normal rangeWinter 2024–25: highest 0.47 m · 9 days above the normal rangeWinter 2025–26: highest 0.60 m on 27 January 2026 · 55 days above the normal range’93–94’99–00’11–12Record 0.75 m, 1993Top of normal range
1990–912025–26
The highest days on record
  • 30 December 19930.75 m
  • 24 December 19990.72 m
  • 7 July 20120.69 m
  • 22 December 20120.61 m
  • 27 January 20260.60 m
  • 4 November 20230.59 m

The River Wey has topped its normal range on 679 days since 1990, most in the winters of 2012–13 and 2023–24. By its highest day, the winter of 2025–26 was the 5th-highest of the 36.

Environment Agency Hydrology API, Broadwey (station 44109), daily maximum level; the record and normal range from the EA’s stage scale. Live river levels are on GOV.UK’s Check for flooding.

Flood warnings

No flood warning or alert is in force for Weymouth · 128 warnings in 20 years

The Environment Agency has 10 flood warning areas and 4 alert areas reaching into the town; warnings since the service began in 2006.

Now: no flood warnings or alerts for Weymouth (checked 5 November 2026, 20:16). Check for flooding on GOV.UK →
Warnings and alerts each year for areas in Weymouth
06
07
08
09
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
Flood warning (flooding expected)Flood alert (flooding possible)

The warning area covering the most of Weymouth, Groundwater flooding in the West of Dorset, has not had a flood warning since 2006. Of the 128 warnings, 47 were for Dorset coast at Preston Beach and 43 for River Wey from Upwey to Weymouth.

2014 had the most warnings (44). The most recent warning was on 18 February 2026.

Show the 14 warning and alert areas
AreaKindSince 2006Now
Dorset coast at Preston BeachWarning area47None
River Wey from Upwey to WeymouthWarning area43None
Portland Harbour at Ferry BridgeWarning area25None
Groundwater flooding in the West of DorsetWarning area0None
Weymouth Seafront at The EsplanadeWarning area6None
Weymouth Seafront at Chelmsford St, Crescent St, Derby St, and Stanley St in WeymouthWarning area3None
Weymouth Harbour at Lakeside Walk, Hope Street and Nothe ParadeWarning area3None
Weymouth Seafront at Weymouth TownWarning area1None
Weymouth Harbour at Weymouth HarboursideWarning area0None
Weymouth Harbour at Weymouth TownWarning area0None
East coast of DorsetAlert area168None
West coast of DorsetAlert area157None
Weymouth Rivers and StreamsAlert area90None
Weymouth HarbourAlert area75None

Environment Agency Historic Flood Warnings (first issues only, not updates; “flood watch” counted as an alert before 2011) and the real-time flood-monitoring API. Sign up for free warnings on GOV.UK or call Floodline, 0345 988 1188.

Radon

Parts of Weymouth are in radon Affected Areas, up to the Over 30% band

Radon is a natural radioactive gas from the ground; long exposure raises the risk of lung cancer. The atlas gives the chance that a home in each 1 km square is above the UK action level (200 Bq/m³).

SY6478: Under 1% of homes above the action levelSY6479: 1–3% of homes above the action levelSY6577: 1–3% of homes above the action levelSY6578: Under 1% of homes above the action levelSY6579: 1–3% of homes above the action levelSY6580: 1–3% of homes above the action levelSY6581: 1–3% of homes above the action levelSY6582: 1–3% of homes above the action levelSY6583: 1–3% of homes above the action levelSY6675: Under 1% of homes above the action levelSY6676: Under 1% of homes above the action levelSY6677: Under 1% of homes above the action levelSY6678: Under 1% of homes above the action levelSY6679: 1–3% of homes above the action levelSY6680: 1–3% of homes above the action levelSY6681: 1–3% of homes above the action levelSY6682: 1–3% of homes above the action levelSY6683: 1–3% of homes above the action levelSY6684: 10–30% of homes above the action levelSY6685: Over 30% of homes above the action levelSY6776: Under 1% of homes above the action levelSY6777: Under 1% of homes above the action levelSY6778: 1–3% of homes above the action levelSY6779: 1–3% of homes above the action levelSY6780: 1–3% of homes above the action levelSY6781: 1–3% of homes above the action levelSY6782: 1–3% of homes above the action levelSY6783: 1–3% of homes above the action levelSY6784: 5–10% of homes above the action levelSY6785: 5–10% of homes above the action levelSY6877: Under 1% of homes above the action levelSY6878: 1–3% of homes above the action levelSY6879: 1–3% of homes above the action levelSY6880: 1–3% of homes above the action levelSY6881: 1–3% of homes above the action levelSY6882: 1–3% of homes above the action levelSY6883: 5–10% of homes above the action levelSY6981: 1–3% of homes above the action levelSY6982: 1–3% of homes above the action levelSY6983: Over 30% of homes above the action levelSY6984: Over 30% of homes above the action levelSY7081: 1–3% of homes above the action levelSY7082: 1–3% of homes above the action levelSY7083: 3–5% of homes above the action levelSY7084: 3–5% of homes above the action level© OpenStreetMap contributors · BGS/UKHSA
Under 1%1–3%3–5%5–10%10–30%Over 30%
Share of the town’s area in each band
Under 1% of homes23%
1–3% of homes68%
3–5% of homes4%
5–10% of homes1%
10–30% of homes2%
Over 30% of homes2%

77% of Weymouth’s built-up area is in a radon Affected Area (1% of homes or more above the action level), and 5% in squares of 5% or more, mostly on the north side of the town.

The squares are indicative: each takes the highest band found anywhere inside it, so most homes in a coloured square are below it. Only a three-month test in the home gives a real answer.

BGS/UKHSA Indicative Atlas of Radon in Great Britain, version 3. Check an address at UKradon.org.

Neighbours

Flood risk in the places around Weymouth

Share of homes at high or medium and at low risk from rivers and the sea. Tap a town for its page.

Chickerell: Hazard risk CFortuneswell: Hazard risk DGrove: Hazard risk AWeston: Hazard risk ASouthwell: Hazard risk ADorchester: Hazard risk B−Charminster: Hazard risk CChickerellFortuneswellGroveWestonSouthwellDorchesterCharminsterWeymouth
ABCD
TownPeopleHigh or mediumLowHazard
Weymouth55,5401.7%1.8%C−
Chickerell3,9731.5%2.5%C
Fortuneswell4,5546.7%0.4%D
Grove1,0320%0%A
Weston5,2080%0%A
Southwell1,7000%0%A
Dorchester21,3580.4%1.2%B−
Charminster1,7321%0.6%C

Fortuneswell, 4 miles south, has the most homes at risk around Weymouth (6.7% at high or medium). Grove, Weston and Southwell have none.

Be ready

Get ready for what Weymouth faces

Free warnings, what to do in a cloudburst, and what to check before you move.

Get the warnings
  • Sign up free for Environment Agency flood warnings by text, call or email.
  • Floodline: 0345 988 1188, 24 hours.
  • Weymouth’s warning areas include Groundwater flooding in the West of Dorset and River Wey from Upwey to Weymouth.
Sign up ↗
In a cloudburst
  • Surface water rises in minutes, often with no warning issued: stay out of underpasses and dips.
  • Keep the gullies and drains outside your home clear of leaves.
  • Report a blocked road drain to the council.
Radon
  • Test over three months, in a living room and a bedroom.
  • Above 200 Bq/m³, a small sump and fan usually fixes it.
  • New homes in radon areas are built with protection: basic from 3%, full from 10%.
UKradon ↗
Before you buy or rent in Weymouth
  • Check the address on GOV.UK’s long-term flood risk service: it gives rivers and sea and surface water separately.
  • Ask whether the home has flooded or had a flood insurance claim; the TA6 property form asks the seller.
  • Homes built before 2009 can get flood cover through Flood Re, the government-backed scheme; newer homes can’t.
  • Check radon for the address on UKradon.org (a small fee) or ask the seller for a test result.
How to read these numbers

What this data can and can’t tell you

  • Defences are counted. Both agencies’ maps allow for flood defences and the chance they are overtopped or fail, so a town behind a defence scheme can show few homes at high risk and many at low risk.
  • Surface water is our estimate. Neither agency publishes a count of homes at risk from surface water, so we read each address on the map. A flat on a hill and a basement in a dip can share a postcode.
  • One town, many streets. Risk is street by street. Check a specific address on GOV.UK’s long-term flood risk service before you buy or rent.

Check the long-term flood risk for an address on GOV.UK →

Questions about flooding and hazards in Weymouth

Does Weymouth flood?

1.7% of homes are at high or medium risk from rivers and the sea on the Environment Agency’s maps, which allow for flood defences. About 6.7% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Weymouth grades C− for hazard risk against UK towns.

Which parts of Weymouth are at risk of flooding?

From rivers and the sea, the places the Environment Agency warns directly: Dorset coast at Preston Beach, River Wey from Upwey to Weymouth, Portland Harbour at Ferry Bridge and Weymouth Seafront at The Esplanade. Surface water can collect in low spots anywhere in the town. Check a specific address on GOV.UK’s long-term flood risk service.

Is Weymouth at risk of surface water flooding?

About 3.6% of homes are at high risk and 3.2% at medium risk from surface water, against 1.7% at high or medium risk from rivers and the sea. Surface water floods come with little warning, and the agencies don’t issue warnings for them.

Is radon a problem in Weymouth?

77% of the town’s built-up area is in a radon Affected Area on the BGS/UKHSA atlas, and 5% is in 1 km squares where 5% or more of homes may be above the action level. Most homes are below it; a three-month test is the only way to know.

Are there flood warnings in Weymouth now?

No flood warning or alert was in force near Weymouth at 5 November 2026, 20:16. Live warnings are on GOV.UK’s Check for flooding service and Floodline, 0345 988 1188.

Contains Environment Agency information © Environment Agency and/or database right 2026. Contains British Geological Survey materials © UKRI 2026.

Sources: Environment Agency Risk of Flooding from Rivers and Sea, postcodes in areas at risk (June 2026); Natural Resources Wales Flood Risk Assessment Wales (May 2026); ONS Census 2021 households by postcode · Environment Agency Risk of Flooding from Surface Water (NaFRA2, 2025) and Natural Resources Wales Flood Risk Assessment Wales surface water and small watercourses, read at every address (ONS National Statistics UPRN Lookup, September 2026) and weighted by Census 2021 households by postcode · Environment Agency Hydrology API (daily maximum river level) and flood-monitoring stage scales · Environment Agency real-time flood-monitoring API · Environment Agency Historic Flood Warnings (January 2006 to June 2026) and flood warning and alert areas · BGS/UKHSA Indicative Atlas of Radon in Great Britain, version 3, by 1 km square · TownRatings grades: our own summary of the data, ranked against UK towns only. All under the Open Government Licence v3.0.

Contains public sector information licensed under the Open Government Licence v3.0. Contains HM Land Registry data © Crown copyright and database right 2026. Contains OS data © Crown copyright and database right 2026 (ONS boundaries). Northern Ireland: Source: NISRA; contains Land & Property Services data and Ordnance Survey of Northern Ireland information, © Crown copyright, licensed under the Open Government Licence v3.0. Scotland: contains National Records of Scotland data, Registers of Scotland data and SEPA data, © Crown copyright / © SEPA 2025, licensed under the Open Government Licence v3.0.