MetService has issued a severe thunderstorm watch for parts of the country.

Gisborne, Hawkes Bay, Manawatu, Tararua, Kapiti-Horowhenua, Wairarapa, Wellington, Marlborough, Christchurch and Canterbury Plains are all being warned of the severe weather conditions.

People in these areas should be on the lookout for threatening weather conditions and monitor for possible Severe Thunderstorm Warnings. A Severe Thunderstorm Watch means conditions are favourable for severe thunderstorms in and close to the watch area.

This is an alert to the potential development of severe thunderstorms with very heavy rain, large hail and damaging winds.

Conditions are favourable for the development of severe thunderstorms about eastern areas from Canterbury northwards to Gisborne today.

A period of severe westerly gales possible about Hawke's Bay south of Hastings and the Tararua District.

A west to southwest flow covers New Zealand until Thursday, with strong or gale force winds forecast for many regions.

Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, as well as make driving conditions hazardous.

Wind gusts of this strength can cause some structural damage, including trees and power lines, and may make driving hazardous.

Please keep up to date with forecasts in case any changes are made.

For information on preparing for and keeping safe during a storm, see the Civil Defence Get Ready website.