Motorway traffic has already slowed Aucklanders with a serious of crashes creating traffic jams.
A crash on the Southern Motorway heading north just before the Mt Wellington off-ramp about 10.30am has created heavy traffic through the area.
While it had since been cleared, traffic remains heavy from Tip Top corner to Market Rd.
Earlier, citybound traffic was heavy on the Northwestern Motorway between The Causeway and St Lukes, while citybound traffic on the Southern Motorway was slow from Manukau to Ellerslie.
A crash just after 7am blocked a citybound lane on the Southern Motorway at Takanini, while a crash on State Highway 1 between Warkworth and Puhoi also caused delays.
Elsewhere snow has been falling on the mountains while the West Coast has had heavy rain.
Early this morning a MetService severe thunderstorm watch was in place from Hamilton to Cape Reinga, which threatened to affect Auckland's morning commute and any motorists attempting to make an early long-weekend getaway.
The watch had now been lifted after the front moved in overnight with embedded thunderstorms that threatened to bring severe rain, hail and squally winds, the forecaster said.
The front was now making its way east across Northland towards the Coromandel.
The wild weather has left Auckland looking at a high of 18C today before the winter freeze hits, sending temperatures to 14C and 13C on Saturday and Sunday.
Monday is tipped to be the pick of the long weekend weather with a break in the rain and high of 16C.
However, fellow forecaster WeatherWatch is now tipping two more cold blasts to hit Auckland and the country next week, with both having the potential to bring wild winds capable of bringing down power lines.
The first would hit briefly on Wednesday before a second storm followed on Friday.
"WeatherWatch has already advised utilities in Auckland of possible power outages one week from now as this blast of windy weather comes in," the forecaster said.
The NZ Transport Agency is also urging motorists to be careful across the country today as roads turn potentially hazardous with heavy long weekend traffic and changeable weather.
It's warning holidaying motorists heading north out of Auckland to expect heavy traffic from 1pm-6pm today. Traffic is then tipped to be heavy with returning weekenders coming south into Auckland on Monday between 10.30am-6pm.
Those travellers heading south out of the city should expect heavy traffic today from 10.30am through to 7.30pm.
Police national manager of road policing Superintendent Steve Greally also issued a statement telling motorists to "stay alert, be patient, and don't rush".
"More than 160 people have died on our roads this year. Tragically, many of those deaths could have been prevented if everyone took these four simple and proven road safety actions that prevent serious injury and death on our roads," he said.
"Make sure everyone has their seatbelts on, remove distractions and stay focused on driving, don't get behind the wheel if you've been drinking or are tired, and drive at a safe speed for the conditions."
Travellers heading north for the long weekend can expect highs of 15C and 14C in Whangārei this Saturday and Sunday, before the rain clears on Monday for a high of 16C.
Whitianga in the Coromandel is expected to reach a high of 14C on Saturday and Sunday before a cloudy Monday with a top of 15C.
Traffic heading north and south between Wellington and the Kapiti Coast is also expected to be heavy over each day of the long weekend, NZTA said.
The capital can expect a windy and wet high of 15C today, before the temperature drops to 12C and 9C on Saturday and Sunday. Monday should be mainly fine with a high of 13C.
However, the worst of the rain had passed through Wellington overnight when there was about 60mm of rainfall in the ranges and wind gusts up to 118km/h on Rimutaka summit.
In the South Island, Christchurch is tipped for a high of 14C today before the temperature plummets to a wet and wintry 8C and 9C on Sunday before the weather turns fine on Monday for a top of 12C.
Overnight temperatures will drop to a freezing 1C on Saturday and Sunday nights.
Traffic is being delayed north west of Christchurch where one person was trapped after a car and tanker truck crashed on Oxford Rd (SH72), west of Cust, near Poyntz, police said.
Emergency services rushed to the scene and got to work freeing the person.
St John said a helicopter took one person to Christchurch Hospital in a critical condition.
SH72 was currently blocked.
Elsewhere in the South Island, the West Coast has been hit with deluges of rain after overnight heavy rain warnings from the ranges west of Nelson to Buller and Fox Glacier.
Arthur's Pass was the wettest place in the country over the past 24 hours with about 200mm of rainfall in the area.
MetService's Moes said it had been a very active past few days weather-wise in New Zealand.
"In the last 24 hours, we've seen 8500 lightning strikes, mainly in the west of the South Island in the west and central parts of the North Island," she said.
Water Safety NZ has also called for Kiwis to keep safe around rivers and waterways over the long weekend.
"Anyone heading out into the outdoors for a walk, a hike, to hunt or to fish needs to be careful around rivers and other waterways," chief executive Jonty Mills said.
"Rivers running at high levels are extremely changeable and unpredictable and incredibly dangerous.
"Rivers generally account for a third of all preventable drownings and last year the deadliest activity was accidental immersion.
"That's why we are urging people to use caution around water."
Snowfall was expected to affect State Highway 8 at Lindis Pass with falls to about 600m yesterday along with the Crown Range Rd and Milford Rd (SH94).
However, the larger dumps of snow were not expected until tomorrow with the southerly cold front blows in, Moes said.
The freezing weekend across the country has been likened to a weather hangover by National Institute of Water and Atmospheric Research (Niwa) meteorologist Chris Brandolini after months of warmer than average temperatures.
However, despite a second cold snap being due to hit late next week, the overall outlook for winter was for temperatures to be normal or above average, he said.
Today's weather
Whangārei
Morning rain then occasional showers, all with possible squally thunderstorms and hail. 19C high, 10C overnight.
Auckland
Morning rain then occasional showers, all with possible squally thunderstorms and hail. 18C high, 9C overnight.
Hamilton
Morning rain then occasional showers, all with possible squally thunderstorms and hail. 16C high, 7C overnight.
Tauranga
Rain with possible squally thunderstorms and hail. 18C high, 9C overnight.
Rotorua Rain with possible squally thunderstorms and hail. 14C high, 6C overnight.
New Plymouth Periods of rain, with squally thunderstorms and hail at times. 18C high, 9C overnight.
Napier A period of morning rain, then becoming fine. 18C high, 9C overnight.
Whanganui Rain, possibly heavy, clearing afternoon but returning evening. 18C high, 8C overnight.
Wellington Any remaining rain clearing early but returning evening. 15C high, 8C overnight.
Nelson Fine spells with the chance of showers, then rain from evening with possible heavy falls. 15C high, 5C overnight.
Christchurch Rain developing this evening. 14C high, 4C overnight.
Dunedin Cloudy periods with a shower or two. Rain from evening. 10C high, 5C overnight.
