Whanganui is the latest region to come under a severe thunderstorm watch today.
MetService says thunderstorms are expected to affect western parts of the North Island from Waikato southwards until Thursday evening, bringing localised very heavy rain, hail and squally wind gusts.
The areas included in the latest watch are Waitomo, Taranaki, Whanganui, Manawatū, Kāpiti-Horowhenua, Wairarapa and Wellington.
Between 8am and 2pm Thursday, there is a risk that a few thunderstorms could be severe south of Raglan, bringing rain with damaging wind gusts of more than 110km/h and one or two small or damaging tornadoes.
"Wind gusts of this strength can cause some structural damage, including to trees and power lines, and may make driving hazardous.