Scattered thunderstorms are expected to develop over the northern part of Hawke's Bay this afternoon.
The thunderstorms are not expected to track as far south as Napier and Hastings, with the ranges as well as Gisborne, Taupo, Rotorua and the Bay of Plenty the most likely places they will develop.
The thunderstorm, expected between 1pm and 7pm, could bring localised downpours of 25-40+ mm of rain.
The thunderstorm is associated with a cold front moving up the North Island.
MetService is warning residents that driving conditions will be hazardous and flash flooding can occur with rainfall of this intensity.
A police spokesperson said, "If you're driving in the rain there are several things you can do to help keep yourself and others safe on our roads:
"If it's wet enough to put your wipers on, it makes sense to put your headlights on as well.
"Slow down. It helps you brake more gently and gives you enough time to react and retain full control of your vehicle.
"Watch your following distance to the vehicle in front, you need more stopping distance.
Don't forget to buckle up
Showers are expected throughout the day in Napier and Hastings after a dollop of much needed rain overnight.
A southerly change will also see temperatures and humidity drop.