A 47-year-old female was thrown from a car when it went down a bank near Waipukurau yesterday.
Senior Sergeant Dan Foley said police were called to the crash in Ashley Clinton at 12.45pm.
The car had gone down the bank near the bridge that runs over the Tukituki River.
The serious crash unit was called to the scene and a number of police attended.
The woman was "slipping in and out of consciousness" and was airlifted to hospital by the Lowe Corporation rescue helicopter, he said.
A statement said the woman received leg and spinal injuries. She was transported to Hawke's Bay Hospital for further treatment.
The other passenger escaped with minor injuries.
Both were discharged from hospital a few hours later, a hospital spokesman said.
There were four other crashes at the weekend. The first was early on Saturday morning where emergency services were called to a car in the ditch on SH2 at Waipatu, in Hastings District. At 9.28am, a car rolled on SH50 on Mareakakaho Rd at Roys Hill, then just after noon near the Mohaka Bridge another vehicle rolled. An ambulance attended all three cases. Also yesterday at 8.21am there was a minor crash at the intersection of Frederick St and Karamu Rd north.
It has been a busy week for emergency crews in the Bay, attending a further eight road incidents last Thursday.
Puketitiri, Farndon, Tukituki, Kennedy, Napier-Taupo and Links roads all had traffic accidents during the day, with some victims requiring medical treatment.
Mr Foley said the unusually high number was likely due to the sudden change in weather.
"At the end of the day people need to drive to the conditions and adapt their driving if they change."
He said the bottom line was that wet roads were more dangerous. "We don't want a repeat of last week."