Frosts had been recorded in the city every day so far this week but until yesterday there were no reports of vehicles crashing.
Senior Sergeant Denton Grimes of the Rotorua police said yesterday morning saw several incidents where motorists had lost control on the ice.
No one had suffered serious injuries.
In one of the incidents, a light truck landed on its side after the driver lost control on the ice.
The truck was travelling on Tarawera Rd, heading towards Tikitapu (the Blue Lake), when it crashed about 9am.
The road was covered in black ice and traffic was diverted along Okareka Loop Rd in a bid to prevent further accidents.
Rotorua weatherman Brian Holden said he recorded the -8.5C frost from his Springfield weather station overnight on Monday and believed that was one of the coldest the city had experienced. This follows frosts recorded last month of -5.5C.
"There was a -8.5C frost, which is the heaviest frost we've had for some time," Mr Holden said.
"That was an extra cold one."
The all-time lowest minimum temperature is -5.2C on August 16, 2011, but it was recorded at a different site from where Mr Holden does his recordings.
Mr Holden said that in a normal winter, a -6C frost was as cold as it got. He was unable to confirm whether Monday's frost was the coldest on record but said it was the coldest one he could remember.
He said Tuesday had an overnight low of -2.4C with yesterday morning's frost temperature reading -4.5C.
Mr Holden said some areas of Rotorua could have frosts and icy roads throughout the day.
"Some areas of road which are in the shade and don't get much sun can stay icy all day and then there could be another frost which would make it worse."
Rotorua man Mike Tennent was out running shortly after 9am on Monday and said the morning was the coldest he had experienced this season. Mr Tennent, who is a regular runner, rugged up more than usual.
"I have only bothered with the gloves and beanie once before and had taken them off after a couple of kilometres, however [on Monday] they were on until the last couple of kilometres."
Mr Grimes said yesterday's incidents were a reminder to motorists to take care.
"With the cold snap roads can become icy and police are encouraging motorists to drive to the conditions. They need to slow down and take care and be aware of known icy roads."
Meanwhile, MetService media and communications meteorologist Daniel Corbett said the crisp, sunny weather looked set to hang around for the rest of the school holidays.
He said Rotorua was set to be fine until Monday, when rain is expected to hit the city.
Mr Corbett said Rotorua was set to become warmer too.
"It's going to be slowly getting less cold."
Niwa senior climate scientist Georgina Griffiths said it was possible parts of Rotorua had recorded a frost of -8.5C.
"[Yesterday] morning was one of the coldest days of the year for most."
Niwa recordings are done at Rotorua International Airport and the lowest recording they have is -5.2C on August 16, 2011.
For Monday morning they recorded a temperature of -0.1C and in the last 39 days at Rotorua Airport, nine of them registered an air frost (below 0C) with the lowest being -3.6C on June 30.
She said that in the 40 years of records there had been 14 occasions when recordings of -3.6C or lower had been taken at Rotorua Airport.
She said Rotorua had had an unusually frosty June and start to July.