A severe thunderstorm watch has been issued for the Bay of Plenty, meaning there is a risk for thunderstorms to become severe and small tornadoes.

The watch is in place for Northland, Auckland, Great Barrier Island, Coromandel Peninsula, Bay of Plenty and Rotorua.

"Scattered heavy showers and thunderstorms are expected to develop over Northland, Auckland and Coromandel Peninsula later this afternoon and evening," says the MetService.

"There is a moderate risk of these thunderstorms becoming severe, producing localised downpours of 25 to 40mm/hr, strong wind gusts of 90 km/h and a chance of small tornado."

Closer to home, heavy rain with embedded thunderstorms is expected over the Bay of Plenty this evening and overnight.

"There is a moderate risk of these thunderstorms becoming SEVERE, producing localised downpours of 25 to 40mm/hr, strong wind gusts of 90 km/h and a chance of small tornado, until about midnight tonight."