HA8: 39 m clear of the highest tide in the London Bridge ledgers

The lowest postcode in HA8, HA8 0DP, stands 39 m above the highest tide in the London Bridge ledgers (5.41 m, 1 February 1953). The highest, HA8 8DF, stands 103 m above it.
- Ground at eight in ten of its postcodes: between 51 m and 72 m, measured from Ordnance Datum; the middle one stands at 60 m.
- None lies in the Environment Agency's Flood Zone 3 from the sea.
- Mostly in Barnet; partly in Harrow.