Yes, though the risk comes from rain, and no river or sea is involved. The hill has no river or sea flood zone on it at all. About a quarter of its postcodes still rate high on at least one flood measure. That comes from rain with nowhere to drain, running off the slopes and pooling at the bottom of them. Upper Norwood is high and dry in the way people usually mean, and wet in the way it actually floods.
None of Upper Norwood's postcodes falls in the Environment Agency's river-and-sea flood zones. That covers zone 3, the highest-probability band, and zone 2, the separate medium-probability band around it. For a district on one of the highest ridges in south London, that makes sense.
Surface water is a different matter. When heavy rain falls faster than the drains can take it, it runs down the roads and gathers wherever the ground flattens or dips. The River Effra still flows under Upper Norwood Recreation Ground, buried in the 1940s. A buried river still follows the shape of the land, and so does the rain running off the hill above it.
The Environment Agency's climate-adjusted mapping, which allows for heavier rain and higher rivers in future, still puts none of the area's postcodes in a river or sea flood zone. That forward look covers rivers and the sea only. It has nothing to say about the rain in the roads.
For insurance, the clear river-and-sea result is helpful, because that is the flooding that tends to drive premiums up hardest. Insurers also look up surface-water ratings postcode by postcode, though, and a home in one of the high-rated postcodes may be quoted on that basis. Get a buildings insurance quote on the exact address while you are still deciding whether to offer. The flat at the bottom of a slope and the one at the top can share a postcode district and get very different prices.
Across the 590 postcodes with a rating, about 25% rate high on at least one flood measure, about 23% medium and about 38% low. These ratings count any of several measures, surface water included, so a postcode gets a high rating if any one of them is high. With rivers and the sea ruled out, the high ratings here come from the other measures. That is why a hilltop can score worse than its location suggests.
The modelled flood extents show no postcodes in a high-risk area either with defences counted or without them. On this ridge the question of defences never comes up, because the modelling finds no river or sea flooding for a defence to hold back. Surface water has no equivalent wall, only the drains.
The nearest tide gauge is at Portsmouth, a measure of how far this ridge is from the sea. It recorded sea level rising by about 2 millimetres a year between 1962 and 2023. That is a rate measured on the coast over those years, and it has little bearing on a hilltop in south London.
The Environment Agency's records show no historic flooding in the area. That is reassuring, but a clean record only covers the floods someone wrote down, and a road that floods for an afternoon after a cloudburst rarely makes it into the books.
Flooding is a weak point for Upper Norwood, and the reason is surface water off the hill, with no river or sea risk at all. How much it matters depends on whether a home stands at the top of a slope or at the bottom of one.