Caernarfon Flood Risk

Rivers and the sea Low a 0.1% to 1% chance in any year

Surface water Not mapped No national band is published for this source

Groundwater Not mapped Natural Resources Wales publishes no groundwater likelihood band

Reservoirs Not mapped Reservoir flood maps are not published as a likelihood band in Wales

Caernarfon has a Low flood risk from rivers and the sea , with 1.7% of homes in a Medium or High band.

Caernarfon has 9,754 residents and 4,312 homes. Ranked 209 of 621 in Wales for rivers and sea flood risk.

Why Are Parts Of Caernarfon In Flood Zone 3 But Rated Low Risk?

10.8% of postcodes in Caernarfon fall in Flood Zone 3, but the flood risk band for rivers and the sea is low. The two maps measure different things: the Flood Zone ignores defences, and the band counts them.

Why a Flood Zone 3 house can be Low risk

When Has Caernarfon Flooded Before?

The Environment Agency holds 3 recorded flood outlines covering Caernarfon, the most recent dated 26 December 2015.

Absence of a record is not evidence that a place has never flooded — the Environment Agency states that a lack of coverage does not mean an area has never flooded.

What Does Caernarfon's Flood Risk Classification Mean?

10.8% of postcodes in Caernarfon sit in Flood Zone 3, the planning band for land with a 1% or greater annual chance of river flooding or 0.5% or greater of sea flooding — and the map that draws it deliberately ignores flood defences.

The flood risk band for rivers and the sea is Low , with 1.7% of homes in a Medium or High band. Unlike the Flood Zone, the band counts the defences that are actually in place, which is why the two can describe the same street differently and both be right.

Caernarfon is one of the places where they disagree most in England: a large share of its postcodes are in Flood Zone 3, yet few of its homes carry a Medium or High band. The gap is the defences — land the planning map must treat as floodplain, behind a barrier that lowers the present-day chance of flooding.

Flood Zone versus flood risk band: the full comparison

Which Postcode Districts Cover Caernarfon?

Each district below is one postcode district that falls inside Caernarfon. The band is the one shared by most of that district's postcodes, so it describes the district rather than a single street — enter a full postcode in the checker for one address. A district can cover more than one town, and the district pages linked from the checker are keyed to the town that holds most of its postcodes.

Postcode districts covering Caernarfon, with the flood risk band shared by most of each district's postcodes. A district can span more than one local area, so its band is a summary and not a property-level answer.
Postcode district	Postcodes here	Rivers and sea band	Surface water addresses
LL55	260	Low	not published for this district

What Else Is Near Caernarfon?

Flood risk in Wales How this nation classifies flood risk, and its gaps
What each flood risk level means The annual chance behind each band word