UPDATED 11.56AM: Forecasters say the latest cold snap to hit the country is extremely rare for this time of year.

The snow has arrived early to the lower South Island and the Desert Road - and most parts of the country are in for a cold and blustery start to the day.

MetService forecaster Peter Little says it isn't often that such wintry conditions arrive in the middle of April.

"This sort of event is really what you'd usually see in the middle of winter. So for this time of year it is unusual."

"Unfortunately we won't see the end of the cold weather, because then it's a great recipe for potentially the first frosts of the year."

Weather forecaster Richard Green believes the cold snap last night could be a premonition of what's to come, but thinks it'll be a bit more of a mixed bag this winter.

"I personally think we're look at a very changeable winter. I think we're going to see some frosty days and clear days but also some warm spells but mixed with some very cold spells like what we've seen in the last day or two."

AA motoring affairs manager Mike Noon says across the country, people need to drive to the conditions and be ready for them to change.

If you were hoping for a bit more of the summer weather we've been having, you might be out of luck.

South Island 

It was a frigid morning in the South Island as the unseasonal cold snap hit. 

Newstalk ZB's Scarlett Cvitanovich says it was a rough night in Christchurch.

"Cold weather blast hit Christchurch overnight, it was quite a noisy night, there was hail and thunderstorms and even a bit of snow falling in the central city."

Cvitanovich says the temperature in central Christchurch was around one degree at midnight... but the wind chill sent the mercury plummeting to minus-six.

Residents in the suburb of Cashmere woke up to a blanket of fresh powder which continues to coat the Port Hills.

It isn't all 'winter wonderland' in the city: Last winter residents in the Flockton Basin were slammed by numerous floods, which spurred urgent remediation work.

Mayor Lianne Dalziel says they are better prepared this time with one pump operational and targeted work underground - but there are no guarantees.

"People are going to have to be prepared themselves. We've got a good relationship with the Metservice to make sure that we are looking ahead, but sometimes those downpours can actually be quite targeted."

The NZTA is warning Southern drivers not to get caught out with black ice this morning.

Southland Manager Peter Robinson says despite better conditions, the messages for people on the work commute are the same.

"Everyone should drive as if the road is icy and snowy even if it looks clear. Reduce speed, particularly approaching corners, and allow plenty of time so there's no pressure to get to work."

A broken down truck is causing delays of up to an hour along State Highway One between Dunedin to Waitati.

North Island 

It was a noisy and blustery start for the day in Auckland.

A band of torrential showers is passing over the city with thunder and lightning and a little hail in some areas.

The wind and rain has brought down some trees, mainly in the rural areas of Helensville and Kumeu to the west of Auckland, there's surface water on some roads - and firefighters say lightning's set off some alarms.

Conditions are expected to improve significantly later in the day.

People living in the small central North Island town of Ohakune say they've never had snow this early in the year - the township at the base of Mt Ruapehu received a good blanket of snow overnight.

Resident Kathy says the town and surrounding areas are all white.

"It was a nice surprise to wake up to our dusting snow which would have been about six centimetres."

"It's fun. I love it!"

"What we can see is it looks beautiful. That snow is so low. It's got to be down to around about fourteen-hundred metres. It looks quite thick from fourteen-hundred up and then a dusting down the bottom." 

The icy conditions have sparked warnings for motorists travelling between Taihape and Hunterville, as well as State Highway Four.