Mild Spring weather came to an abrupt halt this afternoon when severe thunderstorms hit the Auckland, Waikato and Waitomo regions.

About 30mm of rain fell along with hail 20mm in diameter, and wind reached gusts of 110km per hour.

The temperature dropped suddenly in a few minutes from the maximum high of 20C to under 13C.

MetService ambassador Bob McDavitt said the storms started on Auckland's North Shore about 4pm before travelling northwest of Hamilton, where they were due to ease about 8pm.

He said there may have been about 450 strikes of lightening but most were from cloud to cloud, with only about 10 hitting the ground.