"So far our rain gauges don't show dramatic figures in terms of the amount of rain, but there has been about 6mm on the Kaimai Range in the last two or three hours," he said.
Doolin said across the central north island there had been about 30 lightning strikes in the last couple of hours but most were not cloud to ground strikes.
There had been no reports of damage, he said.
Doolin said people in the warnings areas should be on the lookout for threatening weather conditions and monitor for any possible severe thunderstorm.
Rainfall of this intensity can cause surface and/or flash flooding, especially low-lying areas such as streams, rivers or narrow valleys, and may also lead to slips, he said.
Doolin said some of the rainfall was not related to the developing thunderstorms but to a cold front crossing the central north island.
"Once the front pushes its way off the North Island overnight the weather is expected to return to more familiar settled conditions the central north Island has been experiencing."
Doolin said however, another low-pressure system was developing in the Tasman Sea and around the Bass Straights and behind it was another cold front, he said.
This is expected to bear down on the country early next week but the weather outlook including the amount of rain the front will bring was a little bit uncertain, he said.
Motorists were urged to ensure they drove the conditions Driving conditions will also become hazardous with surface flooding and poor
visibility in heavy rain.
For information on preparing for and keeping safe during a storm, visit the Civil
Defence Get Ready website.