MetService communication meteorologist Lisa Murray says a low is bringing severe winds to Northland.
It is possible that low will track a bit further south bringing severe winds to Auckland.
"MetService is just really advising people to keep up to date with the latest forecast. Check in overnight and tomorrow morning."
There is a warning out for winds in Northland and a watch out for Auckland, which could be upgraded to a warning depending on the position of the low.
Ms Murray said gusts could reach 100km/h or more, especially in exposed places.
Today most of the country is in for rain or showers, MetService says.
Squally thunderstorms and hail are also possible in the west of both islands, MetService meteorologist Hannah Moes says.
"Most places will see rain or showers today; more so in western areas," she says.
"There's a high risk of squally thunderstorms and some severe weather warnings are in place, with heavy rain expected in parts of Fiordland, Westland and Buller."
Kapiti, Wellington and the central North Island may also experience patches of heavy rain, she says
Auckland will have a few showers clearing later in the day. Rain is expected to spread overnight in the city of sails with thunderstorms possible.
"The place to be today is Gisborne or Hawke's Bay," Ms Moes says. "They'll remain dry with gusterly northwesterlies and warm temperatures in the low to mid 20s."
The east of the South Island would have a period of rain this morning and then be mostly fine.
On Saturday, a south to southwest change will move up the country, she says.
"There's a severe weather watch in place for severe gales in Auckland and Northland.
"There'll be rain for most of the North Island with a risk of thunderstorms for the northern half.
"The South Island will become fine in the west with showers in the east, continuing through to Sunday."
Central parts of the North Island will become fine on Sunday, she says.
"The worst of the weather is in the North Island today and tomorrow, then there'll be an improving trend.
"There may just be a few showers at the top and bottom of the North Island on Sunday."
Meanwhile, WeatherWatch is predicting unsettled and stormy weather around the country today.
"The front pushes over the South Island during the morning and afternoon, and then over the North Island during the afternoon and evening.
"It mainly moves in from the west, so as can be expected, western regions of both islands will have rain with heavy falls and thunderstorms, as well as rain squalls at times.
"The east coast of the South Island sees thick high cloud, along with a few spots of rain as the front moves over in the afternoon, then cloud breaking away to some sun -- though winds blow strongly from the western quarter.
"The east coast of the North Island sees high cloud thicken from morning, while there's also perhaps a spot of rain in the evening. Otherwise conditions stay mainly dry, while westerlies and northwest winds blow strongly."
MAIN CENTRES FORECAST
A few showers clearing for a time. Northwest strengthens. High 23C.
Saturday: Rain, heavy thundery falls. Strong northwest changing to southwest late. High 19C.
Sunday: Showers clearing in the evening. Strong southwesterlies. High 18C.
Today: A few showers clearing for a time. Northwest strengthens. High 21C.
Saturday: Rain, heavy thundery falls. Strong northwest changing to southwest late. High 18C.
Sunday: Showers clearing in the evening. Strong southwesterlies. High 17C.
Today: Sunny spells, showers from the afternoon. Northwest strengthens. High 20C.
Saturday: Rain, heavy thundery falls. Strong northwest changing to southerly late. High 18C.
Sunday: Fine weather. Strong southerlies easing. High 18C.
Today: Rain developing, thunder from evening. High 19C.
Saturday: Rain, heavy thundery falls. Strong northwest changing to southerly late. High 16C.
Sunday: Becoming fine early. Strong southerlies easing. High 16C.
Today: Morning showers, rain from afternoon. Strong northerlies. High 16C.
Saturday: Periods of rain. Gale southerly change midday. High 14C.
Sunday: Showers and gale or strong southerlies. High 13C.
Today: Brief morning rain, becoming fine. Northerly, strong at times. High 19C.
Saturday: Showers develop in the morning. Strong southwesterlies. High 14C.
Sunday: Occasional showers. Strong southwesterlies. High 12C.
Today: Showers clearing in the afternoon then fine. Northerly turns southerly. High 14C.
Saturday: Showers develop in the morning. Southwesterly strengthens. High 12C.
Sunday: A few showers. Strong southwesterlies. High 12C.
- Source: MetService