A Severe Thunderstorm Watch has been issued by MetService for Waikato, Waitomo, Taumarunui, Bay of Plenty, Rotorua, and Taupo.

"Rain is expected over the north of the North Island this afternoon and evening," says a MetService spokesperson. 

"This rain will be heavy with intensities of 10 to 25 mm per hour and be accompanied with thunderstorms.

"However about Waikato, Waitomo, Taumarunui, Taupo, and the Bay of Plenty including Rotorua, there is a moderate risk of localised downpours, with or without thunderstorms, bringing intensities of 25 to 40 mm per hour."

MetSerivce says the risk of downpours is expected to decrease in Waikato, Waitomo and Taumarunui by early evening, and in Bay of Plenty and Taupo late evening.

This Severe Thunderstorm Watch is valid for eight hours from 1pm - 9pm today, Sunday, December 31.

Rainfall of this intensity can cause surface and/or flash flooding, especially about low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips.

Driving conditions will also be hazardous with surface flooding and poor visibility in heavy rain.

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

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