Yes. Windsor has a real flood risk, and almost all of it comes from the Thames, the river that put the town here in the first place. About one in ten postcodes are in the highest river flood zone. About a quarter rate high for flooding on at least one measure. Most homes are outside the worst of it. The risk runs along the river, and so does a good part of the town.
In the Environment Agency's river-and-sea flood zones, about 9% of Windsor's postcodes are in Flood Zone 3, the highest-probability band. Another 16% are in Flood Zone 2, the medium-probability band just outside it. The two bands don't overlap, so between them about a quarter of postcodes are in a mapped river flood zone. Floods here aren't hypothetical. The Environment Agency has 164 recorded flood events for the area, covering about 16% of it. The latest, in December 2000, came from the main river, and the record gives the cause as channel capacity exceeded with no raised defences. In other words, the river ran out of room and nothing had been built to hold it back.
Surface water, the rain that collects before it ever reaches a river, isn't broken out separately in the figures here. It is included in the postcode indicators covered further down, so any street can be affected, including the ones well away from the Thames.
The Environment Agency also models how the zones could spread as the climate changes, and on that basis about 26% of postcodes are covered. That is a model of how the zones could grow, not a date by which those streets will flood.
For insurance, a house in Flood Zone 3 or with a recorded flood is likely to cost more to insure. Some insurers may set a higher excess or decline the risk, and a resilient survey can help. Particulars will mention a "Thames view" and leave the flood zone out. The insurer will ask about the zone first.
The postcode indicators combine river, sea and surface water. On those, about 25% of Windsor's postcodes rate high on at least one measure, about 31% medium and about 61% low. A postcode counts in every band where at least one measure puts it, so the three shares overlap, and none of them should be added to the zone figures above. The zone figures are the cleaner picture. These indicators show how many postcodes are flagged once rain is included.
Counting homes instead of postcodes, the Environment Agency's rivers-and-sea mapping puts 145 properties at high risk, 127 of them homes, 250 at medium risk, 3,420 at low risk and 649 at very low risk, out of 5,514 properties counted. That total includes only properties in postcodes with some risk, which is why it is smaller than the town. Most of Windsor's flood exposure is low risk spread over a wide area, plus a few hundred properties where it is serious.
The Environment Agency's flood extents also show whether a defence is present. About 9% of postcodes are in the high-risk extent with no defence in the model, and about 2% are in the high-risk extent with one. Where a defence appears in the model, it only means a defence exists. It doesn't make the property safe. On these figures, most of Windsor's high-risk postcodes have nothing modelled between them and the river.
The nearest tide gauge, at Portsmouth, recorded sea level rising by about 2 millimetres a year between 1962 and 2023. That gauge measures the Channel, a long way downstream, and for Windsor the river matters far more than the sea.
Flood risk is Windsor's weak spot, and a poor one for a town this desirable. Before you offer on anything near the river, look up the exact address on the Environment Agency's flood map and get an insurance quote.