Niwa says lightning detectors show there have been more than 2500 strikes around New Zealand and the eastern Tasman Sea so far today.
MetService says thunderstorms started lashing Northland around 9am. Lightning strikes have been detected in the southern part of the region.
Auckland is also set for electrical storms this morning.
MetService says the front is expected to cross Auckland from mid-morning to early afternoon bringing with it a burst of heavy rain.
Thunderstorms are likely across parts of the upper North Island.
Earlier this morning a “cluster of thunder cells” were heading towards Auckland and Northland, invigorated by the subtropical jet stream.
A heavy rain watch came into force for Auckland and Northland from 8am. Rain is expected to fall until after lunch and MetService advises amounts may approach warning criteria.
The forecaster says the top of the country will experience a period of heavy rain and isolated thunderstorms.
The front is expected to clear the North Island overnight and the forecast for Saturday and Sunday is looking much more settled as high pressure dominates.
The only fly in the ointment for a generally dry forecast across the country is a front expected over the lower South Island on Sunday.
