Three people travelling in a bakkie on the R103 near the Escort hospital were killed around 2.30am on Saturday, spokesman Robert Mckenzie said.
Seven other occupants were taken to hospital, four of them were in a critical condition.
Nine other people were injured when a bakkie they were travelling in was involved in an accident on the N2 near Tongaat on the north coast around 4am, he said.
They sustained serious and minor injuries and were transported to nearby hospitals.
Two others were injured when two cars collided on the N2 near the Balito offramp, just after 4am. They were taken to the KwaDukuza clinic for further treatment.
On Friday around 7pm, one person was in a critical condition and another was seriously injured when a heavy goods truck they were travelling in was involved in an accident on the N3 between the Engen and Tugela plaza.
The pair was taken to Ladysmith hospital for further treatment, Mckenzie said.
Mckenzie said the cause of the accidents were not clear and cautioned drivers to be cautious when driving due to the weather conditions.
“The rain, gusting winds and cold temperatures, we experienced yesterday [Friday], continued last night and look, set to continue over the weekend.
“Drivers should slow down, switch head lights onto dim and increase following distances.”