Metservice has upgraded and extended weather warnings in place for much of the Top of the South as a front stalls over the South Island on Thursday.
Heavy rain warnings have now been issued for much of Nelson Tasman from noon on Thursday.
Heavy rain will his Tasman northwest of Motueka first, with an orange heavy rain warning in place from noon Thursday through till 7pm Friday.
The area, which includes Golden Bay, can expect 250 to 350 mm of rain, but possibly as much as 400 mm about the ranges.
Peaks rates of 20 to 30 mm/h are expected during Friday with thunderstorms possible.
The deluge will move across the district with an orange heavy rain warning in place for Nelson and Marlborough between Nelson City and the Awatere River, and also Nelson Lakes National Park.
This area can expect 120 to 180 mm of rain with peak rates of 15 to 25 mm/h expected from Friday morning with thunderstorms possible.
Strong wind is also expected to hit Marlborough southeast of the Awatere River with severe north to northwesterlies gusting 140 km/h in exposed places.
NZTA/Waka Kotahi are urging drivers to take care on the roads with the weather possibly affecting SH60 Motueka to Collingwood, SH6 Hira to Havelock, SH6 Nelson to O’Sullivans Bridge, SH6 O’Sullivans Bridge to Westport SH65 O’Sullivans Bridge to Springs Junction, SH 63 Kawatiri Junction to Renwick and SH 1 Seddon to south of Kaikōura.
"Drivers can expect challenging driving conditions while the bad weather persists and must take extra care on the roads," a statement says.
