A severe thunderstorm watch has been issued for areas including Whanganui and Taihape.
MetService warned on Monday afternoon a line of thunderstorms was approaching the west of the North Island, and was expected to affect western areas this afternoon and evening.
The thunderstorms were expected to bring heavy rain, hail and strong winds gusting 90 to 110 km/h.
There was also moderate risk some of the thunderstorms could become severe, with gusts greater than 110 km/h.
MetService said gusts this strong could cause structural damage, including trees and power lines, and could make driving hazardous.
The weather watch was issued for Whanganui, Taihape, Taranaki, Taumarunui, Waitomo and Waikato.
The wider Whanganui region is on a strong wind watch with gusts expected to be around 90km/h.
Metservice meteorologist Dan Corrigan said most of the Whanganui region was under the watch.
"North of the city towards Taranaki and through to the central plateau around Raetihi, north to northeasterly winds may approach severe gale at times," Corrigan said.
The latest wind watch was issued for the period between 9am and 2pm Monday.
Whanganui's township sat right at the southern border of the wind watch and would likely not experience the heaviest winds, Corrigan said.
"The town is quite sheltered thanks to the rugged terrain to the north. We are not expecting gusts to get that high, but they may approach that. It's only in exposed places where we may see gusts reach those speeds. It will begin easing off on Monday afternoon."
Rain was expected to develop on Monday morning, before turning to showers in the afternoon, possibly heavy.
On Tuesday, a few showers are expected before clearing in the afternoon with fine spells increasing.
Wednesday's forecast is looking more promising, when strong westerlies should have eased and the temperature is forecast to move up to 14C. Cloudy periods and a shower or two are possible.
By Thursday and Friday, forecasts are for mostly fine weather, with temperatures expected to reach a high for the week of 19C on Friday.