The torrential rain that has caused havoc in the Nelson region for the last three days appears to be easing, with conditions expected to improve overnight in most places.
MetService lifted heavy rain warnings in the Bay of Plenty, Taranaki, Nelson and northern Marlborough this afternoon but heavy showers and isolated thunderstorms were still possible in some areas, said meteorologist Dan Corbett.
In the Nelson-Tasman district the downpour has flooded roads and homes, caused slips, brought down power lines and contaminated water.
More than 100 businesses and homes were damaged in Stoke, Richmond and Hope.
Emergency services have received more than 500 calls since yesterday afternoon. Most were for flooding, including a medical emergency when someone received an electric shock while trying to turn off the water in their flooded property.
Tasman District Council warned Motueka residents to boil their water for at least a minute before drinking it after yesterday's deluge.
In one hour last night 104mm of rain was recorded in Upper Roding and 100mm in Stoke.
A subtropical trough over the region was expected to have passed by this evening, and cooler, fresher air would start coming in from the Tasman, possibly bringing more rain but in much lower quantities, said Mr Corbett.
The warm northerlies of sub-tropical air fuelling the heavy downpours were set to ease as the winds shifted to the west, reducing torrential rain and the risk of further flash flooding.
Severe warnings have tonight been issued for the ranges of northern Westland, Buller, the western ranges of Nelson and the Tararua range where heavy rain and isolated thunderstorms are possible tomorrow and Wednesday.
Rainfall was expected to ease in the remaining affected areas, said Mr Corbett.
"The winds were going to shift to the west later today into tonight and then it was just going to be more of a typical westerly showers and that very heavy rain risk would start to ease.
"Up towards the north west it's already starting to dry out. It's lost its intensity. That drier air is starting to filter into the north west of the Nelson region so it's looking more promising."