Firefighters have responded to more than 850 calls overnight - with severe gusts and intense downpours in the centre of the country

More than half were from the Wellington Region - but every part of the North Island except Northland's reported storm damage or flooding.

Manawatu-Whanganui 's red warning has been downgraded to orange, with the same applying to the lower North Island, Kaikoura, Banks Peninsula and parts of Canterbury.

Slips and fallen trees are blocking roads, some schools are closed, and Wellington's rail, ferry and regional flights are impacted.

Wellington Region Emergency Management's Sam Bishop says close to 40 thousand homes are without power across Wellington, Wairarapa and Hutt Valley.

He says the power companies did indicate they hope to restore all power by tomorrow morning - with no details of when and where.