Heavy rain watches have also been issued for the ranges of Westland, south of Otira, from 4am to 5pm today, and the ranges of Buller and Westland, north of Otira, from 11am to 11pm today.
These watches could be upgraded to warnings.
"There is still a lot of uncertainty about total rainfall accumulations."
The North Island's Tararua Range is also in line for wet weather, with a heavy rain watch from 4pm today till 1am tomorrow.
But as the wetter, more changeable weather rolls in over the weekend, overnight temperatures will go up a few notches, after some chilly mornings this week.
"Auckland has a forecast overnight low temperature of 16C on Sunday, a pretty big difference to the 4.7C recorded at Auckland Airport Thursday morning," said MetService meteorologist Ashlee Parkes.
Gisborne and Hawke's Bay may be the best place to be today, with mainly fine weather except for some high cloud. Gisborne is expected to reach a high of 18C and Napier 20C.
Showers turn to rain this afternoon from Taranaki to Kāpiti, including Taumarunui and Taihape, while cloudy periods in Wellington, Wairarapa, Marlborough and Nelson will give way to scattered rain from afternoon or evening.
A few spots of rain in the morning will be followed by patchy drizzle and increasing cloud later in the day for Cantabrians and it will be cloudy in Otago and Southland, with rain spreading north from Stewart Island this morning, easing to showers this afternoon.
The mild late autumn weather continues across the country, with temperatures in the high teens for many.
Auckland will reach 19C, Hamilton 17C and Tauranga and Wellington 18C.
It'll be slightly cooler in the south, with 15C in Invercargill and 16C in Christchurch, but Nelson and Dunedin fare slightly better, with 17C expected.
