Wild weather has lashed parts of the country, with the upper South Island and Wellington regions mopping up after flooding and slips.

Several roads in the Nelson/Marlborough areas were closed yesterday as rivers burst their banks, and farmland copped the brunt of it, with some stock losses likely. But the rain had eased and river levels had dropped by late yesterday, allowing roads to reopen.

More than 100mm fell in some areas in the hours leading up to yesterday morning. Heavy rain also caused surface flooding and slips in the Wellington region, with one slip causing a commuter train to derail at Plimmerton, north of the city, and be hit by another coming the other way. Road traffic flows were also affected.

A spokesman for Wellington police said they were responding to a high volume of weather-related incidents.

The MetService said the heavy rainfall was expected to gradually clear.

Some heavy falls were last night also expected in Northland, Auckland, Waikato, Coromandel, Bay of Plenty and Taupo but they were expected to gradually clear today. In Waikato, river levels were being closely monitored yesterday.

Meanwhile, Niwa's National Climate Centre seasonal outlook predicts temperatures in all regions are likely to be above average from October to December. Rain levels in all regions are expected to be near normal or below normal.

In Northland, Auckland, Waikato and Bay of Plenty there was a 60 per cent chance of warmer conditions than average, and a 70 per cent chance of near or below average rain fall.

In the central North Island, Taranaki, Wanganui, Manawatu and Wellington there was a 65 per cent chance of warmer than usual temperatures and 75 per cent chance of near or below average rainfall. In Gisborne, Hawkes Bay and Wairarapa there was a 50 per cent chance of higher than usual temperatures and a 80 per cent chance of near or below average rainfall.

Soil moisture levels and stream flows were likely to be near normal or below normal in most regions. The Mountain Safety Council has urged people to delay trips into the outdoors until the bad weather cleared.

- Additional reporting by NZPA