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C+Hazard risk Grade
Flood & hazards in Aylesbury · Environment Agency

Heavy rain is Aylesbury’s main flood risk: 4.8% of homes, against 0.8% 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. Aylesbury’s Hazard risk Grade is C+: #32 of 39 in Buckinghamshire.

1990worst recorded flood8flood warnings since 200645%in a radon Affected Area
In brief

What stands out about Aylesbury’s hazards

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

Rain, more than the river4.8% of homes sit where heavy rain can flood the streets, against 0.8% at risk from rivers and the sea.Remembers 1990Floodwater covered 91 hectares of today’s Aylesbury in 1990; 1,751 of today’s households live inside past flood outlines.8 flood warnings since 2006For the parts of Aylesbury the Environment Agency warns directly; the most recent on 5 January 2024.Radon in parts3% of the town is in 1 km squares where 5% or more of homes may be above the radon action level.
By hazard

What Aylesbury faces

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

Rivers and the sea

0.8%of homes at high or medium risk
More than the typical UK town · more than 64% of towns
302 homes by the EA’s own count

Surface water

4.8%of homes at high or medium risk
More than 66% of UK towns
Rivers and sea: 0.8%

Past floods

3years with a recorded flood
Last recorded: January 1993
1,751 households inside past outlines

The River Thame

1.94 mhighest in winter 2025–26 at Aylesbury Thame
25th-highest of 35 winters
Record 2.51 m, January 2003

Flood warnings

8flood warnings since 2006
154 flood alerts for the wider area
Last warning 5 January 2024

Radon

45%of the town in a radon Affected Area
Highest band here: 10–30% of homes
3% 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

Aylesbury grades C+ for hazard risk

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

Homes at high or medium flood risk (0.8%)Fewer than 36% 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 Aylesbury

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.

Recorded flood: 1990Recorded flood: 1992Recorded flood: 1993© OpenStreetMap contributors · EA NaFRA2
HighMediumLowrivers & seaHighMediumLowsurface waterAylesbury’s built-up area

The river and sea risk follows the River Thame, the Horsenden Stream and the Chalgrove Brook. 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

0.8% of Aylesbury’s homes are at high or medium risk from rivers or the sea

The Environment Agency’s national map, allowing for defences. A further 4.1% are at low risk.

High risk0.2%of homes · 1 in 30 a year or more101 homes, EA count
Medium risk0.5%of homes · 1 in 30 to 1 in 100201 homes, EA count
Low risk4.1%of homes · 1 in 100 to 1 in 1,0001,598 homes, EA count
Where Aylesbury sits among 3,735 UK towns
35%None
23%Under 0.5%
9%0.5–1%Aylesbury
11%1–2%
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; Aylesbury has more than 64% of towns.

Towns its size: 45th of 86 from the fewest homes at risk
#TownPeopleHigh or med.
1Oldham Greater Manchester110,7220%
2Birkenhead Merseyside109,8540%
3Dudley West Midlands64,2770%
…
43Ashford Kent82,1430.7%
44Nuneaton Warwickshire88,8180.7%
45Aylesbury Buckinghamshire87,9660.8%
46Newcastle-under-Lyme Staffordshire76,5110.8%
47Walsall West Midlands70,7770.8%
…
85Maidenhead Berkshire67,3916%
86Grimsby Lincolnshire85,9158.9%

UK towns of 62,000 to 123,000 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 6.4 times as many Aylesbury 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 water4.8%
Rivers and the sea0.8%
0%10.5%21% of homes

About 2% of homes are at high risk of surface-water flooding (a 1 in 30 chance or more each year) and 2.7% at medium risk: roughly 1,680 households. A further 10% face a low risk from surface water. That is more than 66% of UK towns.

~1,680
households at high or medium risk
10%
of homes at low risk
66%
of UK towns have a smaller share
45,308
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.

Flood history

Aylesbury has flooded in 3 recorded years since 1990, most of all in 1990

Every flood the Environment Agency has mapped inside Aylesbury’s built-up area, newest first. The record is fullest for big river floods; small and surface-water floods are often missing.

  1. 1993January 1993: River flooding recordedUnder 1 hectare inside today’s built-up area
  2. 1992January 1992: River flooding recorded1 hectare inside today’s built-up area
  3. 1990January and February 1990: River flooding recorded91 hectares inside today’s built-up area
The worst: 199091 ha

Floodwater covered 91 hectares of what is now Aylesbury in 1990, the largest flood the record holds here (January and February).

1,751 of Aylesbury’s households today live inside the outline of a recorded flood.

Since 1990, the largest recorded flood inside the town covered 1 hectare.

River levels

The River Thame at Aylesbury Thame: highest 2.51 m, in January 2003

The highest level each winter (October to September) at the Environment Agency’s Aylesbury Thame gauge (Stone), since 1990. The river normally runs between 0.41 m and 1.90 m here.

Highest level each winter, metres
Winter 1991–92: highest 2.45 m on 23 September 1992 · 8 days above the normal rangeWinter 1992–93: highest 2.13 m · 10 days above the normal rangeWinter 1993–94: highest 2.02 m · 5 days above the normal rangeWinter 1994–95: highest 2.04 m · 6 days above the normal rangeWinter 1995–96: highest 2.06 m · 4 days above the normal rangeWinter 1996–97: highest 1.42 m · 0 days above the normal rangeWinter 1997–98: highest 2.07 m · 4 days above the normal rangeWinter 1998–99: highest 2.13 m · 12 days above the normal rangeWinter 1999–00: highest 2.08 m · 5 days above the normal rangeWinter 2000–01: highest 2.35 m on 30 October 2000 · 31 days above the normal rangeWinter 2001–02: highest 2.03 m · 8 days above the normal rangeWinter 2002–03: highest 2.51 m on 2 January 2003 · 14 days above the normal rangeWinter 2003–04: highest 1.77 m · 0 days above the normal rangeWinter 2004–05: highest 2.02 m · 1 days above the normal rangeWinter 2005–06: highest 1.90 m · 1 days above the normal rangeWinter 2006–07: highest 2.47 m on 21 July 2007 · 27 days above the normal rangeWinter 2007–08: highest 2.08 m · 9 days above the normal rangeWinter 2008–09: highest 2.21 m · 6 days above the normal rangeWinter 2009–10: highest 1.73 m · 0 days above the normal rangeWinter 2010–11: highest 1.41 m · 0 days above the normal rangeWinter 2011–12: highest 2.18 m · 8 days above the normal rangeWinter 2012–13: highest 2.14 m · 18 days above the normal rangeWinter 2013–14: highest 2.28 m · 14 days above the normal rangeWinter 2014–15: highest 1.71 m · 0 days above the normal rangeWinter 2015–16: highest 1.85 m · 0 days above the normal rangeWinter 2016–17: highest 1.66 m · 0 days above the normal rangeWinter 2017–18: highest 1.93 m · 1 days above the normal rangeWinter 2018–19: highest 1.60 m · 0 days above the normal rangeWinter 2019–20: highest 2.16 m · 21 days above the normal rangeWinter 2020–21: highest 2.69 m on 4 October 2020 · 36 days above the normal rangeWinter 2021–22: highest 2.05 m · 3 days above the normal rangeWinter 2022–23: highest 1.96 m · 6 days above the normal rangeWinter 2023–24: highest 2.44 m on 5 January 2024 · 42 days above the normal rangeWinter 2024–25: highest 2.28 m · 30 days above the normal rangeWinter 2025–26: highest 1.94 m · 3 days above the normal range’20–21’02–03’06–07Record 2.51 m, 2003Top of normal range
1991–922025–26
The highest days on record
  • 4 October 20202.69 m
  • 2 January 20032.51 m
  • 21 July 20072.47 m
  • 23 September 19922.45 m
  • 5 January 20242.44 m
  • 27 September 20242.38 m

The River Thame has topped its normal range on 333 days since 1990, most in the winters of 2023–24 and 2020–21. By its highest day, the winter of 2025–26 was the 25th-highest of the 35.

Environment Agency Hydrology API, Aylesbury Thame (station 1911TH), 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 Aylesbury · 8 warnings in 20 years

The Environment Agency has 4 flood warning areas and 2 alert areas reaching into the town; warnings since the service began in 2006.

Now: no flood warnings or alerts for Aylesbury (checked 13 November 2026, 03:06). Check for flooding on GOV.UK →
Warnings and alerts each year for areas in Aylesbury
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 Aylesbury, Bear Brook and tributaries, from Walton Court in the Ellen Road area down to St Marys School, has not had a flood warning since 2006. Of the 8 warnings, 6 were for River Thame from North Aylesbury to Chiselhampton and 2 for Bear Brook and tributaries, from Broughton to Haydon Mill Farm in Coldharbour, Aylesbury.

2021 had the most warnings (3); 2024 the most alerts (25). The most recent warning was on 5 January 2024.

Show the 6 warning and alert areas
AreaKindSince 2006Now
River Thame from North Aylesbury to ChiselhamptonWarning area6None
Bear Brook and tributaries, from Broughton to Haydon Mill Farm in Coldharbour, AylesburyWarning area2None
River Thame from Long Marston to North AylesburyWarning area0None
Bear Brook and tributaries, from Walton Court in the Ellen Road area down to St Marys SchoolWarning area0None
River Thame, Horsenden Stream and Chalgrove BrookAlert area102None
Bear Brook and tributaries in the Aylesbury area, including Wendover and Weston TurvilleAlert area52None

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 Aylesbury are in radon Affected Areas, up to the 10–30% 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).

SP7814: Under 1% of homes above the action levelSP7815: Under 1% of homes above the action levelSP7816: Under 1% of homes above the action levelSP7913: Under 1% of homes above the action levelSP7914: Under 1% of homes above the action levelSP7915: Under 1% of homes above the action levelSP7916: Under 1% of homes above the action levelSP8012: 3–5% of homes above the action levelSP8013: Under 1% of homes above the action levelSP8014: Under 1% of homes above the action levelSP8015: Under 1% of homes above the action levelSP8111: 10–30% of homes above the action levelSP8112: 3–5% of homes above the action levelSP8113: 3–5% of homes above the action levelSP8114: 3–5% of homes above the action levelSP8115: Under 1% of homes above the action levelSP8116: Under 1% of homes above the action levelSP8210: Under 1% of homes above the action levelSP8211: Under 1% of homes above the action levelSP8212: 3–5% of homes above the action levelSP8213: 3–5% of homes above the action levelSP8214: Under 1% of homes above the action levelSP8215: Under 1% of homes above the action levelSP8216: Under 1% of homes above the action levelSP8311: Under 1% of homes above the action levelSP8312: Under 1% of homes above the action levelSP8313: 3–5% of homes above the action levelSP8314: 3–5% of homes above the action levelSP8412: Under 1% of homes above the action levelSP8413: 3–5% of homes above the action levelSP8512: Under 1% of homes above the action levelSP8513: Under 1% of homes above the action level© OpenStreetMap contributors · BGS/UKHSA
Under 1%3–5%10–30%
Share of the town’s area in each band
Under 1% of homes55%
3–5% of homes42%
10–30% of homes3%

45% of Aylesbury’s built-up area is in a radon Affected Area (1% of homes or more above the action level), and 3% in squares of 5% or more, mostly on the south 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 Aylesbury

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

Bierton: Hazard risk ABroughton: Hazard risk AStoke Mandeville: Hazard risk B+Stone: Hazard risk AWeston Turville: Hazard risk B−Aston Clinton: Hazard risk BWingrave: Hazard risk ABiertonBroughtonStoke MandevilleStoneWeston TurvilleAston ClintonWingraveAylesbury
ABCD
TownPeopleHigh or mediumLowHazard
Aylesbury87,9660.8%4.1%C+
Bierton1,2510%0%A
Broughton2,1680%0%A
Stoke Mandeville2,8550%0.3%B+
Stone2,0810%0%A
Weston Turville1,8350.2%1.5%B−
Aston Clinton5,511under 0.1%under 0.1%B
Wingrave1,4980%0%A

Aylesbury has more homes at high or medium risk than any neighbour in the table.

Be ready

Get ready for what Aylesbury 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.
  • Aylesbury’s warning areas include Bear Brook and tributaries, from Broughton to Haydon Mill Farm in Coldharbour, Aylesbury and Bear Brook and tributaries, from Walton Court in the Ellen Road area down to St Marys School.
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 Aylesbury
  • 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.
  • Past floods are what was recorded. The flood outlines come from surveys, aerial photographs and reports; many small floods, and most surface-water floods, were never mapped.
  • 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 Aylesbury

Does Aylesbury flood?

The last flood the Environment Agency recorded inside the town was in January 1993. 0.8% 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 4.8% of homes are at high or medium risk from surface water, when heavy rain overwhelms the drains. Aylesbury grades C+ for hazard risk against UK towns.

Which parts of Aylesbury are at risk of flooding?

From rivers and the sea, the places the Environment Agency warns directly: River Thame from North Aylesbury to Chiselhampton, Bear Brook and tributaries, from Broughton to Haydon Mill Farm in Coldharbour, Aylesbury, Bear Brook and tributaries, from Walton Court in the Ellen Road area down to St Marys School and River Thame from Long Marston to North Aylesbury. Surface water can collect in low spots anywhere in the town. Check a specific address on GOV.UK’s long-term flood risk service.

When did Aylesbury last flood?

The recorded flood outlines inside the town run from 1990 to 1993 (3 years); the largest was in 1990. Flood warnings have been issued for parts of the town since 2006, most recently on 5 January 2024.

Is Aylesbury at risk of surface water flooding?

About 2% of homes are at high risk and 2.7% at medium risk from surface water, against 0.8% 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 Aylesbury?

45% of the town’s built-up area is in a radon Affected Area on the BGS/UKHSA atlas, and 3% 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 Aylesbury now?

No flood warning or alert was in force near Aylesbury at 13 November 2026, 03:06. 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 Recorded Flood Outlines and Natural Resources Wales historic flood map, inside the ONS 2022 built-up-area boundary · 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.