Rain on dry roads can be as slippery as ice, warns Horizons Regional Council road safety co-ordinator Debbie Webster.
"Rain is fantastic news for our region at the moment and we'd like to see more of it, but these kinds of showers can pose a hazard for drivers after long, dry spells," said Ms Webster, the road safety co-ordinator for the Tararua and Horowhenua.
"Dust, dirt, oil and a multitude of other material builds up on the road surface. When it rains after being dry for so long, this greasy cocktail can make the road surface extremely slippery.
"Nicknamed summer ice, it's similar to driving on black ice in winter. Because drivers can't see it, it can lead to potentially deadly situations particularly if drivers aren't aware and don't adjust their driving to suit the conditions."
Ms Webster said the greatest risk to drivers was just after the onset of rain, but it could affect the road surface for hours.