Snow was expected to reach within 500m of sea level today and may rise to 700m tomorrow where it will be "touch and go" as to whether it snows or rains, he said.
Mr Adams said this was particularly concerning as the weather may turn "sleety" and make for bad driving conditions.
The New Zealand Transport Agency has issued an area warning for the Napier Taupo Rd due to snow and the Taihape Rd has been closed from the Rangitikei end through to the Kaweka Forestry headquarters on the Hastings side.
MetService had also forecast that rainfall accumulations south of Napier from Thursday night to Friday afternoon may reach warning criteria.
Temperatures in the Bay this week are expected to drop into low double figures and reach freezing temperatures in the evenings.
While Mr Adams said the weather should "fine up for the weekend" he said the cold weather wouldn't be going away.
"It's going to be cold for a while."