A severe thunderstorm watch is in place for Whanganui.
The line of thunderstorms is coming from the southwest and heading northeast with the watch in place until 11am on Friday.
There's a potential for these thunderstorms to produce damaging wind gusts at an excess of 120km per hour, as well as large hail.
Metservice Meteorologist Dan Corrigan said wind gusts of this strength could cause structural damage including to trees and powerlines and can make driving hazardous.
"My advice would be to heed the severe thunderstorm watch and stay safe," Corrigan said.