Police are urging people to drive to the conditions after a horror night in which four people died on the roads, including a crash that was witnessed by the victim's friends.
Now a truck driver and long-time safety campaigner who was caught up in the chaos has added his voice, pleading with people in an emotional Facebook post to slow down.
AJ Quinn filmed his raw message moments after a woman's car slid into the path of a logging truck rounding a bend on State Highway 29 near Karapiro at 4.50am today.
"We're five days out from Christmas and some family's going to get a s*** call this morning," Quinn said on the video, posted to Facebook soon after the crash.
"Slow down, slow the f*** down, drive to the conditions and get home safe."
The woman's vehicle hit the truck side on, and the driver's side took the full impact. The 24-year-old driver died at the scene.
Her friends were driving ahead of her and watched the crash in horror through the rear-view mirror of their car as her vehicle collided with the truck.
"A bit of a s*** start to the day," Quinn tells viewers.
"I just want to reiterate the message that I put out the other week. People aren't awake, they're not f***en listening to what's going on.
"Unfortunately this is the result," he says, showing the crash scene behind him.
Quinn said he didn't mean to be "gory" by showing the scene, but he wanted the message to get through.
His video has been viewed more than 200,000 times since he posted it this morning.
Matamata-Piako road policing Sergeant Dean Kaio said the woman's vehicle had slid into the path of the logging truck as it rounded a bend.
The cause of the crash had not yet been determined but it had been raining heavily about half an hour before.
Kaio said the woman was heading towards Matamata in wet conditions when the crash occurred near the Hinuera quarry.
"It actually hosed down about half an hour before so there were quite deep puddles when arrived. It was a 75km/h advisory corner but I couldn't tell you how fast she was going."
The woman was one of four people to die in crashes throughout the country overnight, including Bay of Plenty, and two in Otago.
A motorist died near Oropi in the Bay of Plenty when a car left the road and hit a tree about 10.15pm, and a driver was killed after a car left the road and crashed into a paddock in the Clutha District.
Police said the single-car crash happened about 11pm, between Switzers and Moncurs Rds.
A fourth man died in the Waitaki District about 1.50am when his car crashed into a bridge between Herbert-Hampden and Woodburn Rds in Herbert.
Waikato Senior Sergeant Simon Cherry said a man was in a critical condition after his motorcycle and a car crashed on Heaphy Tce, Hamilton, at 10.20pm.