"It will be showery with isolated thunderstorms," he said.
But there was some sunshine today for parts of the country.
Hamilton, Taupo and around the Waikato had occasional showers and fine breaks; while those in New Plymouth and Palmerston North saw similar conditions - with temperature highs around the mid-teens.
Things looked much brighter in and around Tauranga, Gisborne and Rotorua, where there were sunny spells forecast today and a temperature high of 18C in Whangarei.
In the South Island, Nelson, Blenheim, Christchurch, Ashburton and Timaru were mainly fine today.
Christchurch had a temperature high of 11C with a chilly 5C high overnight.
Cold southwesterly winds were expected and those in Invercargill would be in for a cold night, with an overnight high of 3C.
Meanwhile snow is expected to fall on a number of South Island state highways from this evening and continuing until tomorrow morning.
MetService has issued snow warnings for South Island's Lewis Pass, Arthur's Pass, Porters Pass and Lindis Pass this evening which could continue to tomorrow morning.
Another spell of snowfall was likely on Tuesday afternoon and evening in some areas, MetService meteorologist Lisa Murray said.
A spokesman for MetService said although there had been surface flooding in some parts of the country over the weekend - including in Timaru - there had been no major weather incidents last night.
It's been revealed the West Coast has just endured its wettest May ever, smashing a 139-year-old record.
May 1877 had stood as the record of 561mm - until 9am yesterday when it was eclipsed by 8mm at the official rain gauge at Hokitika Airport.
A further 5mm of rain overnight pushed it out further to a whopping 574mm.
"It is the wettest May ever in Hokitika," weather observer Mark Crompton said.