Bad weekend weather grounds air show

Bad weather has forced the start of a major air show to be postponed, as much of the country braces for stormy conditions.

Organisers of the popular three-day event Wings over Wairarapa have announced this morning's opening session at Masterton's Hood Aerodrome has been halted by the elements.

There are heavy showers and high winds in the area and organisers say they're hoping to make a decision on the evening show by noon.

This morning MetService forecast afternoon and evening thunderstorms across much of the North Island and upper part of the South Island - with high humidity and winds producing very unstable conditions.

Thunderstorms may produce rainfall rates of 10 to 25mm/hr and perhaps even small hail.

In a smaller area from Taumarunui to inland Hawkes Bay, Manawatu and Wairarapa, MetService said there is even a moderate risk of severe thunderstorms producing localised downpours of 25 to 40mm/hr.

Auckland woke to scattered showers and moderate wind this morning, though conditions are expected to deteriorate by 8pm, when the rain - possibly heavy - is set to kick in.

Canterbury is forecast to be cloudy with patchy light rain or drizzle.