Thunderous downpours have caused at least 20 big slips around Wellington, blocking roads, burying parked cars and forcing residents from their homes, reports Britton Broun in today's Dominion Post.

MetService spokesman Bob McDavitt said a front had brought heavy rain to most of the country north of Hokitika on Saturday night. Some "grunty" showers followed from around midnight.

Wellington had had 36 millimetres of rain, along with dramatic thunder and lightning.

Five young Aro Valley flatmates evacuated their "Devon St mansion" yesterday after a massive slip eroded its foundations, the tide of mud blocking the road and slamming a parked car through a barrier fence.

Grayson Leonard, 22, and Sam Geers, 20, were asleep when part of the hillside gave way about 6am.

Mr Geers felt tremors but went back to sleep.

"It sounded kind of like thunder in the distance shaking the windows. But when I got up I saw it. About a third of our lawn, the whole patio area and the barbecue we'd built was just gone," he said.

In Farnham St, Mornington, a 15-cubic-metre slip that undermined a public accessway half-buried Peter Chapman's parked car and damaged another just after 9am yesterday.

Mr Chapman, who lives above the slip, said his car was fully insured but the council should have done something after a slip in May covered a neighbour's car only a few metres up the road.

He had been told the risk of another slip was low and there was no money in the budget for reinforcing the cliff so the cost would have to be shared by residents.

"If this had happened during the week my wife would've been putting our kids in the car."

Wellington City Council spokesman Richard MacLean said all dangerous slips were taken seriously but, with hundreds of kilometres of roads cut into hillsides around the city, it was impossible to reinforce them all.

The council was working on installing retaining walls and Farnham St would be looked at. Other large slips were reported in Miramar, Kilbirnie, Mt Cook, Kelburn, Houghton Bay, Northland, Karori and Khandallah.

Mr McDavitt said more showers could be expected today, but an anti-cyclone would bring light winds and clear skies to most areas till Thursday.