Only minor injuries were reported from the two-car crash, which was blocking one lane of SH1. Contractors were en-route to clear a fuel spill.
Police reminded drivers of the need to drive to the conditions and slow down in heavy rain.
Traffic flows into Auckland today were steady and without major incident.
The New Zealand Transport Agency (NZTA) said it seemed many holidaymakers came home yesterday.
Earlier today there were some traffic delays throughout parts of the upper North Island as a result of a number of crashes.
Traffic was also flowing well into Wellington, and NZTA described it as a typical Sunday afternoon's traffic. There was no major queuing around the Otaki area, and it seemed the returning holiday traffic has been spread out over the last three days, NZTA said.
Meanwhile, one of New Zealand's top road cop has urged drivers to take care following four fatal crashes in as many days.
Three people have died in crashes this weekend, bringing this year's road toll to four.
Police said one person was killed when a car crashed into a tree and burst into flames in Bay of Plenty this morning. The fatality came after two people died in separate crashes yesterday, and a motorcyclist was killed on Thursday.
Assistant Commissioner of Road Policing, Dave Cliff, said any death was too many and this year's road toll was already "a terrible waste of human life''.
He urged drivers returning from holiday destinations to take care on the roads today.
"You're better to arrive safe and uninjured than try and rush and never get home at all,'' he said.
"The weather is terrible, so the simple reminders about turning headlights on - you still see people with no lights or driving with park lights, which are completely useless.''
Mr Cliff said drivers needed to keep speeds down and increase following distances so they had more time to stop on wet roads.
Drivers should also make sure the road ahead was clear before overtaking other traffic.
"Probably the most dangerous thing people will be doing is overtaking. Overtaking typically involves driving on the wrong side of the road at speed.''
This morning's fatality was the second this weekend involving a car crashing into a tree. Police said the driver, who was the only person in the car, was dead when emergency services arrived at the scene on Thornton Rd, just north of Whakatane, about 6am.
Firefighters extinguished the flames, which had engulfed the car, and were helping police with their investigation.
Yesterday morning, 38-year-old Georgina Rawinia Rikiti died in hospital after the car she was driving crashed into a tree on Astley Ave in New Lynn, Auckland.
Police said a serious crash unit investigation was expected to take several weeks.
Last night, a man was killed when his motorcycle collided with a car on State Highway 1 in Waikato.
Police said the car's occupants were treated for non-life threatening injuries after the crash near Taupiri about 10pm. The police serious crash unit was investigating.
Another motorcyclist was "very lucky'' to have survived a collision with a bus on a railway overbridge in Horowhenua yesterday, police said.
The man suffered moderate injuries to his lower back and cuts to his body after the crash on SH1 near Whakahoro Rd about 4.20pm. Nobody in the bus was reported injured.
