Yes, parts of Henley flood, and the river is the reason people want to live there. About one postcode in six rates high on at least one flood measure. Around 300 properties sit at high risk from the river. Counting the defences barely changes the high-risk map. Most of the town is dry, and the part everyone photographs is the part to check.
The Environment Agency's river-and-sea flood zones put about 7% of the area's postcodes in zone 3, the highest-probability band, and about 4% in zone 2. The two zones don't overlap. Zone 2 is the medium-probability fringe beyond zone 3, which is why it can be the smaller figure. Together they describe a narrow ribbon along the Thames, not a town under water. The ribbon also happens to be where the riverside houses and the best views are, and nobody lists a house by its flood zone.
Surface water, the flooding caused by heavy rain overwhelming drains rather than a river overtopping its banks, has no separate figure here. It is folded into the postcode indicators further down. Henley's recorded flood history lists 48 events, the most recent in February 2014, and about 5% of postcodes fall within areas that have flooded before. That's recent enough for the people who were there to remember it.
The forward look is less comfortable. Once the Environment Agency adds its climate-change allowance to the flood zones, about 15% of postcodes fall inside the modelled extent. A house that sits outside today's zone can end up inside the future one, and the sales particulars will describe it by the old map.
Insurance follows the address, not the town's reputation. A property in or close to the higher-risk zones can face higher premiums, larger excesses or harder questions from insurers, and a property with a flood claim on record will find the questions harder still. Get a quote on the exact address before you commit, while walking away still costs nothing.
At postcode level, the picture widens because more than one kind of flooding is counted. About 17% of postcodes rate high on at least one flood measure, 15% medium and 28% low. These bands include surface water alongside rivers and sea, so they overlap with the zone figures above. They measure something different and shouldn't be added to them.
The more useful number counts homes rather than postcodes. On the Environment Agency's rivers-and-sea mapping, 299 properties sit at high risk, 117 at medium and 304 at low, out of 1,329 properties in the postcodes listed. Of the high-risk properties, 214 are homes. Only postcodes carrying some river-and-sea risk appear in that count at all, so the rest of the town isn't in the total. Three hundred high-risk properties means three hundred real front doors, which lands harder than a percentage of postcodes.
The question most buyers forget to ask is whether anything stands between the water and the house. In the modelled high-risk extent, about 7% of postcodes are inside it with defences left out, and about 7% with defences counted in. The modelled defences make no difference to the high-risk share. Even where a defence does appear in the model, that only means a defence is present in the modelling. It doesn't mean the property is safe, and it doesn't mean the water has agreed to stop there.
For completeness, the nearest tide gauge is at Portsmouth, where the record from 1962 to 2023 shows sea level rising by about 2 millimetres a year. That is a measured historic rate, not a forecast, and it has little to do with Henley. The threat here is fresh water coming down the Thames, not salt water coming up it.
On flooding, Henley is below average: most of the town stays dry, but the riverside the town is famous for carries real, mapped risk with little defence counted against it. Check the exact address before you fall for the view.