The snow was unlikely to stick around for much longer, said MetService meteorologist Tristan Oakley.
Sleety showers were expected near the summit before turning to rain showers last night.
The sleet and rain should be clear by Wednesday, he said.
Driving on the road was challenging yesterday and drivers were urged to take care, said NZTA Operations Manager Mark Owen.
He urged motorists to plan ahead, allow extra time for journeys, and drive to the conditions.
"Our transport operations centre is open 24 hours a day so we'll be keeping a very close eye on conditions."
The chilly blast comes just after heavy rains caused flooding across the Wairarapa region.
The South Wairarapa District Council has started cleaning up the damage from flooding.
There was no major damage but the bridges had a few broken rails, said Mark Allingham, the council's road and infrastructure services manager.
"Bridges will have to be thoroughly inspected once all flood water has subsided."
Culverts would also need to be checked and cleared so they can handle any further downpours, he said.
Wellington also got a wintry reminder with 165km/h gusts stopping flights, hitting power lines and bringing down trees.
Snow also closed the Akatarawa Rd, between Upper Hutt and Kapiti Coast, yesterday morning.
Winter driving tips
Drive to the conditions.
Allow greater following distances on frosty and wet days.
Obey emergency road closed signs and barriers.
Follow the directions of any road patrol or police officer.
Avoid towing in icy conditions.
It is against the law to drive on a closed highway. If you choose to ignore closures or restrictions, you do so at your own risk, and it voids your insurance.
