Partly, and the part that is at risk is the part everyone wants to live in. Most of the town sits on rising ground and is fine. The low ground is the harbour edge, which is also the postcard. Two-thirds of postcodes here are within a short walk of the sea, and the sea is the hazard, not a river. Flood risk in this town is a question about which street, not whether.
On the Environment Agency's river-and-sea mapping, about 13% of the area's postcodes fall in flood zone 3, the higher-probability band, and about 2% fall in flood zone 2. Zone 2 being the smaller number is not an error. The two are exclusive bands, and zone 2 is the additional medium-probability fringe sitting beyond zone 3 rather than a larger area containing it. In a coastal town with a compact low-lying core, the fringe is narrow because the ground climbs quickly once you leave the water.
Surface water is harder to isolate here. The postcode-level indicator used on this site folds surface water in with rivers and sea rather than reporting it separately, so there is no standalone surface-water share for St Ives to quote. In a town of steep streets draining towards one harbour, that is worth bearing in mind rather than dismissing.
Looking forward, the Environment Agency's climate-adjusted zone covers about 6% of the area's postcodes. That is the allowance for how the extent shifts as conditions change, and it applies to a different footprint from the present-day zones rather than being added to them.
For insurance, expect the address to matter far more than the town. Homes outside the mapped extents will be priced like anywhere else. Homes in the harbour grid can face loaded premiums, higher excesses on flood claims, or insurers who decline flood cover entirely, and a buyer should get an indicative quote on the specific address before instructing a solicitor rather than after exchange.
Pulling the indicators together, about 14% of postcodes here carry a high rating on at least one flood measure, about 23% a medium rating and about 23% a low one. That combined view overlaps with the flood-zone figures above rather than adding to them, because a single postcode can appear in both.
Counted as homes rather than postcodes, the Environment Agency's rivers-and-sea mapping lists 1,695 properties across the postcodes that carry any risk at all, and postcodes with no risk do not appear in that count. Of those, 320 sit at high risk, 462 at medium, 35 at very low and 7 at low. Of the high-risk properties, 139 are residential.
On whether anything stands between the water and the house, the modelling puts about 8% of postcodes inside the high-risk extent with a defence present and about 8% inside it without one, with roughly 9% in the low-risk undefended extent. A defence appearing in the model means it exists on paper, not that a home behind it is safe. There are 25 recorded flood events in this area, and the most recent, in January 2014, came from the sea overtopping defences, which is the plainest possible demonstration of the distinction.
The water is genuinely close. About 66% of postcodes sit within 500 metres of the coast, a threshold the dataset defines rather than a claim about any one address, with a median distance of roughly 280 metres and the nearest postcode about 10 metres from it.
Every postcode here falls under a shoreline management plan, and the stated policy across the 20, 50 and 100 year horizons is to hold the line. That is an intention to maintain defences over those periods, not a promise and not proof that the defences already exist at any given stretch.
At the nearest long-record tide gauge, at Devonport, sea level rose at about 2.35 millimetres a year across the 1962 to 2015 record. That is a measured historic rate, not a forecast for this coast.
Flood risk here sits mid-table: a real and locatable hazard concentrated in the oldest, lowest and most desirable few hundred metres, with the bulk of the town uninvolved. Get the specific address checked, because the average tells you almost nothing about the house you are buying.