Weather: Heavy rain, thunderstorms and strong winds threaten upper North Island, warnings of treacherous road conditions

Auckland is being hit by strong winds and heavy rain on Tuesday night while the Bay of Plenty is expected to bear the brunt on Wednesday morning.

MetService has issued a heavy rain warning for the Bay of Plenty including Rotorua. This rain will develop on Tuesday night and could last until early Wednesday morning. 

"Heavy rain may cause streams and rivers to rise rapidly," MetService warns.

"Surface flooding and slips are also possible and driving conditions may be hazardous."

Heavy rain watches are also in place for Auckland, Northland, and Coromandel. About 6pm on Tuesday, WeatherWatch said winds were peaking in Auckland.

"Take care driving on the Harbour Bridge next 60 minutes in particular with heavy rain and gusts to gale force."

NIWA's forecasting service also urged motorists to drive carefully.

"With heavy rain for Auckland and points east tonight, watch for ponding of water on roads," a post on NIWA Weather's Twitter page said.

"Fallen leaves can block storm drains, causing backups."