A thunderstorm watch has been issued for the Bay of Plenty as heavy rain bears down on the region.

The MetService has issued the watch saying a trough embedded in a moist northwesterly flow is expected to bring heavy rain to central parts of the North Island today.

"During this afternoon and evening, thunderstorms occurring on the trough from South Auckland, Waikato and Waitomo across the central high country to Hawke's Bay (including inland parts of Bay of Plenty and Rotorua) could be accompanied by downpours of 25 to 40mm or more per hour.

"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."

Severe Thunderstorm Watch issued for parts of the North Island. Find all the latest details at https://t.co/GZIq9Jlbrw ^JL https://t.co/ZvDJx8U3cc

— MetService (@MetService) February 13, 2018

Areas affected by the watch include:

Auckland

Waikato

Waitomo

Taumarunui

Bay of Plenty

Rotorua

Taupo

Hawke's Bay

Taihape