Heavy rain, thunderstorms lash upper North Island overnight

Heavy rain, thunderstorms and lightning hit parts of the upper North Island overnight, causing slips and road closures in Thames-Coromandel.

Lightning above Palm Beach, Waiheke Island Source: Supplied/Tobias Roebuck-Ward

At the Pinnacles in the Coromandel, 2cm of rain fell, swelling the Kauaeranga River. Contractors are on site monitoring spillage onto the motorway until the 10am high tide passes.

Thames Valley Civil Defence controller Garry Towler said surface flooding closed State Highway 25 at Hikuai and the Kauaeranga Vallery River Bridge at Rhodes Park.

There were are slips and debris on many roads, and motorists should take care. The East Coast bore the brunt of the storm and teams were out assessing the damage.

More than 50mm of rain fell over parts of Northland and Auckland overnight and Bay of Plenty recorded heavy falls.

The region's dams are half-empty and huge swathes of the country are reeling from one of the deepest droughts the country has experienced.

MetService meteorologist Dan Corrigan said 38mm fell over Auckland Airport and up to 50mm in Coxs Bay.

The rain is forecast to ease to showers, as strong to gale easterlies change to light northerlies this morning in Auckland and this afternoon in Coromandel.

A heavy rain watch is in place of Northland and the Coromandel Peninsula.

The central and lower North Island are due for occasional rain and most of the South Island will have fine weather.