A spectacular lightning show over Nelson late yesterday triggered a forest fire which was still smouldering this morning, cut power, set off alarms and also set the town talking.

The rogue storm with loud rolling thunder, which went on for more than an hour and which the MetService warned of minutes before it started, was captured by many around the region with cameras and phones at the ready.

It provided a spectacular backdrop to a regular evening walk along Tahunanui Beach for the Campion family of Tahunanui.

Ngareta Campion snapped the image of her sons and a friend as they posed on the beach, waiting for a lightning strike, not expecting it would hit quite like it did.

"It was just really good timing. We made them stand there for a few minutes . . . nah, they're just really good posers. They stood there and posed, then the lightning hit."

Judah Grubham, 11, of Stoke, Ezra Campion, 10, and Nikau Campion, 11, appeared indifferent to what must have been an almighty crack behind them, while Shael Campion, 6, took the sensible approach and crouched in front of his brothers.

"They loved the thunder and lightning. It was awesome," Mrs Campion said.

How did last night's storm affect you? Leave your comments below, or click here to send us your stories, photos and video footage

The MetService issued the warning to Tasman and Marlborough at 7.41pm, after radar detected severe thunderstorms near St Arnaud at 7.30pm.

The warning said the thunderstorms were expected to be accompanied by very heavy rain and large hail and the likelihood of surface and flash flooding, leading to hazardous driving conditions and crop damage.

The Ministry of Civil Defence and Emergency Management advised that as the storms approached people should take shelter, preferably indoors away from windows and avoid sheltering under trees.

John Newth of the Nelson Fire Service said a lightning strike started a bush fire in the Hira forest in an area which was inaccessible by road. Helicopters with monsoon buckets have been working through the night and were on site again this morning.

Nelson Marlborough Rescue Helicopter pilot Tim Douglas-Clifford said today that two helicopters were used to fight the fire in the Hira and Lud Valley area. Pilots wearing night vision goggles worked until midnight, and were there again today.

Mr Douglas-Clifford said about half an acre in the middle of the forest had been burned. "It's hard to get crews into. It's smouldering at present and rural fire crews are worried about southwest winds forecast today," he said.

Mr Newth said fire appliances were sent to Todd Bush Rd but could not get to the site.

He said fire crews from Nelson and Richmond were busy attending false alarms, after lightning strikes at the Nelson Pine Industries plant and Sealord plant at Port Nelson triggered alarms in the buildings.

"Driving back from Richmond we could see the storm in the Hira area.

"Lightning strikes on power lines also knocked out power in the Dodson Valley area [Atawhai]."

The Nelson Mail received a great response from readers who sent in photos and comments about the storm.

Rebecca Sellwood photographed the storm from Waterhouse St, Enner Glynn.

"A real meeting of the storms played out in front of us, seemingly one from the north and one from the south. It felt like the gods were at war - it was excellent entertainment for a house full of boys who love mythology."

Sean Barker said a big crowd had gathered at his Princes Dr home to watch the storm.

"They're all frantically clicking in the hope of catching ‘the one'."

Ali Kimber-Bate captured the storm and the brilliant sunset afterwards.

"We had a great front row seat looking over the golf course. My 2 -year-old was initially scared but we started counting between the lightning and thunder to see if it was moving away and it soon turned into a fun evening."

Jimmy Mackay ran to the top of the nearest hill in Atawhai when he saw the storm coming and managed to get a decent screenshot of a lightning strike.

Dean Wratt photographed the storm panorama from Motueka.

"It was such a contrast in the weather, we don't see that a lot around here."

Chris Ratcliffe said his photo of forked lightning on Facebook received 500 "likes".