Yes, part of Lymington is at real risk of flooding, and the part that is can be drawn on a map. This is a town built around a river mouth and open to the Solent, so water is written into the setting. About one home in twelve carries a high risk of surface-water or coastal flooding, and roughly a fifth of postcodes sit within five hundred metres of the coast. The nearest stretch of shoreline is about twenty-five metres from the closest homes. Most of the town is dry and stays dry, but the low ground by the water is exactly where you would expect trouble, and that is where the numbers put it.
For river and sea flooding, the formally mapped zones are narrower than the setting might suggest. A little over two percent of the area falls in the medium flood-risk zone, and close to three percent in the highest zone, the one that carries the greatest chance of river or tidal flooding in any given year. The coast here is managed on a hold-the-line basis, meaning the defences are maintained rather than given up, which is part of why the mapped high-risk band stays as tight as it does around a town this exposed. The sea is rising slowly against the nearest tide gauge, at about two millimetres a year, so the pressure on those defences trends upward over time rather than holding still.
Surface water is the wider worry, because it does not respect the coastline. Alongside the roughly one in twelve homes at high surface-water and coastal risk, about the same share again carry a medium risk, and close to a quarter of the town sits at low risk of it. Heavy rain finding the low points and the drains matters as much here as the tide does, and it reaches streets a purely coastal map would leave looking safe. Around one home in thirty has a record of flooding in the past, which is a small share but not a nil one.
Looking forward, the picture widens. Once the climate allowance is added to the modelling, the share of the area in the higher flood-risk band rises to about one in six. That is the number to weigh if you are buying to hold for decades rather than years, because it is the town the defences and the drains will have to cope with, not the town they cope with comfortably today.
For insurance, the practical effect is address-specific. A home on the dry majority of the town is unlikely to see flood risk move its premium much. A home on the low ground near the river or the front may face higher cover, a flood excess, or questions on the survey, and the help available for the worst-affected homes does not stretch to every property or every situation. The honest step is to get a specific quote for the specific address before you fall for a view of the water.
On flooding, Lymington earns a middle-of-the-road three out of five, and the average hides a split. Buy on the higher, drier streets and the risk is low and easily lived with. Buy on the ground the river and the Solent can reach and you are taking on a real and rising liability, so the only figure that counts in the end is the one for the front door you are actually signing for.