A severe thunderstorm warning has been issued for the Tasman District with campers on the Abel Tasman National Park in line for a direct hit.
Hail is falling in Motueka Valley where one resident says homes have lost power as a powerful storm lashes the region.
"There'll be huge damage to any orchard in its path."
The MetService has just issued a severe thunderstorm warning for parts of the Tasman District.
It says the thunderstorms were detected at 3.45pm near Motueka, Ngatimoti, Riwaka and Lower Moutere.
They are moving north-northwest and are expected to lie near Abel Tasman National Park, Motueka, Totaranui and Tasman Bay at 5.15pm.
"These thunderstorms are expected to be accompanied by very heavy rain and large hail.
"Very heavy rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.
"Large hail can cause significant damage to crops, orchards, vines, glasshouses and vehicles, and make driving conditions hazardous."
A severe thunderstorm watch remains in force for Nelson