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Does Horsham flood? 21 postcodes in Horsham are in the Environment Agency's rivers-and-sea flood-risk data (3 High, 1 Medium likelihood) — the breakdown is further down this page.
No official flood warning is active nearby and the closest river stations are within normal ranges.
Updated 2026-10-10 12:32:07 UTC · Official GOV.UK warnings · Flood preparation & help guide
Horsham is a market town and civil parish on the upper reaches of the River Arun on the fringe of the Weald, in West Sussex, England. The town lies 31 miles (50 km) south-south-west of London, 18.5 miles (30 km) north-west of Brighton and 26 miles (42 km) north-east of the county town of Chichester. Nearby towns include Crawley to the north-east and Haywards Heath and Burgess Hill to the south-east. It is the administrative centre of the Horsham district. In 2018 it had an estimated population of 50,934.
Ordnance Survey places 21 postcodes in Horsham in the Environment Agency's rivers-and-sea flood-risk dataset (Risk of Flooding from Rivers and Sea). Each postcode is counted once, under the worst band any of its properties reaches; together they hold 90 properties in the EA dataset's likelihood bands.
| EA likelihood band | Postcodes (worst band) | Properties in the EA dataset | of which homes |
|---|---|---|---|
| High | 3 | 3 | 0 |
| Medium | 1 | 1 | 1 |
| Low | 17 | 86 | 83 |
| Very low | 0 | 0 | 0 |
| All bands | 21 | 90 | 84 |
This dataset covers flooding from rivers and the sea only — one of five flood sources. Surface water, groundwater, sewers and reservoirs are assessed separately, so a postcode missing from it is not proof that a place cannot flood. The band describes the land around properties (allowing for defences), not any single address and not today's conditions.
Flood-risk bands: © Environment Agency copyright and/or database right 2025. All rights reserved. Some features of this map are based on digital spatial data from the Centre for Ecology & Hydrology, © NERC (CEH). © Crown Copyright and Database Rights 2025 OS AC0000807064. This product is produced in part from PAF® and Multiple Residence Data, the copyright in which is owned by Royal Mail Group Limited and/or Royal Mail Group plc. All rights reserved. Licence number AC0000807064.
Place names: Contains OS data © Crown copyright and database rights 2026. Contains Royal Mail data © Royal Mail copyright and database right 2026. Contains National Statistics data © Crown copyright and database right 2026. Licensed under the Open Government Licence v3.0.
The nearest watercourse on the river map is an unnamed stream, about 370 m from the middle of Horsham's gauges. It flows into the River Arun about 60 m downstream.
A gauge downstream shows water that has already passed this point; one upstream sees it first. Distances along the river are from the point on an unnamed stream nearest the middle of Horsham's gauges. From Ordnance Survey’s river map (OS Open Rivers), which leaves out small streams, ditches and culverts, so a nearer one may exist. This describes where water goes on the map; it says nothing about flooding at any address. Contains OS data © Crown copyright and database rights 2026.
Horsham is monitored by 2 Environment Agency river level stations on the River Arun, in West Sussex. Water levels are updated every 15 minutes, providing real-time flood monitoring for the area.
The River Arun is monitored by 2 stations (Alfoldean, Provender Mill). Each station records water levels continuously, with data synced to FloodRadar every 5 minutes.
There are 6 Environment Agency flood warning areas within 10km of Horsham. When the EA issues a flood warning for any of these areas, it will appear on this page. These include: Boldings Brook in Horsham including Warnham Mill, Redford Avenue, Merryfield Drive, Irwin Drive, Hills Farm Lane, River Walk.; The River Arun at Horsham, from Amiesmill Bridge to Hills Farm Lane, including Millbay Lane, Tanbridge Park, Arunside, and Ridgehurst Drive; Boldings Brook and Chennells Brook through Horsham; The River Arun from Broadbridge Heath to Pallingham Quay, including Broadbridge Heath, Slinfold, Wanford Mill, Gibbons Mill, Newbridge, and Pallingham Lock.
There are 5 storm overflows within 5km of Horsham. None of the 5 with a reporting monitor are currently discharging. Enable "Sewage" on the map above to see their locations.
Each has its own page of live status and past discharges:
If flooding is forecast in Horsham, call Floodline on 0345 988 1188 for the latest information. Move valuables upstairs, turn off gas and electricity if safe to do so, and avoid walking or driving through flood water. Sign up for flood warnings on any station page above to receive email alerts when water levels rise. For emergency numbers, a preparation checklist and insurance guidance, see our flood help & preparation guide.
Horsham gets about 833 mm of rain a year on average (wettest month October, 102 mm; driest July, 51 mm). That is 28% drier than the UK as a whole, which averages 1,163 mm a year. See the rain gauges →
A thirty-year average for the area, not a forecast and not a flood risk on its own. Source: Met Office HadUK-Grid 1991–2020 (5 km grid), 1.8 km away. Average rainfall: HadUK-Grid v1.3.2, Met Office. Contains public sector information licensed under the Open Government Licence v3.0.
Floods whose mapped extent (EA Recorded Flood Outlines) reached within ~5 km of the town centre — most recent first. These are records of mapped extents, not a full list of floods. See them on the map →
Records, not floods: no outline on the record is not evidence a place has not flooded.
Current verdict: Normal. No official flood warning is active nearby and the closest river stations are within normal ranges.
Horsham has river level monitoring on River Arun — 2 monitoring stations in total.
Use the GOV.UK Check for Flooding service (check-for-flooding.service.gov.uk) or call Floodline on 0345 988 1188 (24 hours). You can also set up free FloodRadar email or browser alerts from any station page above.
Follow official advice: move valuables and vehicles to safety, never walk or drive through flood water, turn off gas and electricity if safe, and check on vulnerable neighbours. See our flood preparation guide at floodradar.co.uk/flood-help.
Yes — the Environment Agency's Recorded Flood Outlines dataset shows 1 recorded flood extent around the town centre since 1703, most recently in 1981. That is a count of mapped extents, not of separate floods. Records, not floods: no outline on the record is not evidence a place has not flooded. See the flood history link below.
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