Assistant Commissioner Road Policing, Dave Cliff said after such a long dry period, the build-up of oily residue on road surfaces will create a slippery film when it starts to rain.
"Roads will be extremely slippery for some time and drivers will need to be very careful about speed, following distances and distances it takes to stop."
Mr Cliff says it's also extremely important that people check tyre pressure and tyre tread depth.
"We're asking everyone to take extra care on the roads when the rain does arrive," he said.
- additional reporting Herald on Sunday, nzherald.co.nz