A release from MetService said between 9am and 9pm, snow showers are expected to affect the road.
"Expect 2 to 4cm of snow to settle on the road near the summit, with lesser amounts down to 800m," the release said.
Afront followed by a cold southwest change moved north across the South Island last night and continues across the North Island today.
Another front moved east across the far northeast of the North Island last night. This front brings a period of heavy rain to the ranges of eastern Bay of Plenty and inland Gisborne and a heavy rain watch remains in force for this area.
Meanwhile, today's forecast in Rotorua is for a few showers. There is rain for a time in the late morning, possibly heavy, then clearing by evening. There will be westerlies, changing strong southwest around midday.
The predicted high for Rotorua is 11C and the low 2C.
For Tauranga, MetService's forecast also shows a few showers. There will be rain for a time late morning, possibly heavy, then clearing by evening. Westerlies, changing strong southwest around midday.