Thunderstorms that threatened the North Island earlier today have come to nothing, with just a few lightning strikes up north and in the western Waikato.

MetService said earlier it was possible thundery downpours laced with large hailstones could batter Waikato to Northland across the day, with rain bringing potential flash flooding.

It was set to be the second day of violent thunderstorms after Tuesday saw potentially deadly cloud-to-ground lightning strikes from Whangarei to Waikato.

People were warned to stay inside and keep off the water as more than 600 bolts relentlessly rained down along with hail and driving rain.

Advertisement

But most of today's thunderstorms hit west of Waikato and off the west coast of Northland. A few lightning strikes have also hit near the Kaipara Harbour, MetService meteorologist Peter Little said.

"Yesterday there were very light easterly and westerly breezes on either side of Northland and Auckland which converged, providing a trigger or the uplift to get those thunderstorms going.

"Today the easterly flow was stronger so most of the action was pushed further to the west."

A few thunderclaps and flashes of lightning have hit in the last hour over Waitomo but the trend is very western and drifting out toward the Tasman Sea, Little said.

While the risk of thunderstorms has lowered heavy bursts of rain are still possible tonight.

"We've had heavy showers around southern Auckland and across the Waikato, and up in Northland. There will be some showers over parts of Northland this evening but further south it's an easing trend."

Tomorrow the thunderstorm risk increases again but this time for the central North Island, Little said.

"The sea breezes will push in from the west and meet a light southerly flow which will help the thunder get going.

"We expect thunderstorms from late morning into afternoon - about as far south as
northern Manawatu. There's still a low risk for Auckland and Northland - I wouldn't completely discount some thunder - but again the easterlies up there should make it harder for thunderstorms to form."

Small tornado seen over Auckland

This morning a small tornado was spotted in the sky above an Auckland seaside suburb.

The funnel cloud was spotted spiralling from menacingly dark clouds over Auckland's North Shore.

North Shore resident Jon Bowden was walking his dog on Castor Bay beach this morning when he noticed the twister form in clouds and travel down a street back from the waterfront.

"I was down at the beach walking the dog when I saw the spout come over," said Bowden.

"At first I thought it was a dark cloud but then it had the distinct funnel shape."

He said he watched it move away from him and skirt down a nearby street.

Bowden said it hung in the sky hovering threateningly close to homes for a minute before it quickly dissipated into thin air.

He was unsure if it touched down.

Best said the conditions were ripe for funnel clouds given today's level of instability but the one seen this morning, while impressive, was harmless.