A man in his 50s died after his car left the road and hit a tree in Mogo on the South Coast at 8.30pm.

NSW police from the Bateman's Bay Local Area Command are investigating the circumstances of the crash on the Princes Highway and a report will be prepared for the coroner.

A woman died at 10pm when her car hit a pole on Brush Road at Ourimbah on the state's central coast.

Officers from Tuggerah Lakes Local Area Command are investigating the crash and a report will be prepared for the coroner.

Five people were injured in a head-on collision between two cars in St Ives during a heavy downpour on Monday.

A Toyota Corolla and Mercedes Kompressor collided on the Eastern Arterial Road.

A 56-year-old man who was in the front passenger seat of the Corolla suffered head and chest injuries and was taken to Royal North Shore Hospital in a serious but stable condition. The 18-year-old female driver and 53-year-old male back seat passenger were treated at Royal North Shore Hospital for minor injuries and have since been released.

The 31-year-old female driver of the Mercedes and 28-year-old female passenger were treated at the scene before being taken to Royal North Shore Hospital as a precaution. They were later released.

Officers from the Metropolitan Crash Investigation Unit are investigating the crash and appealing for witnesses to contact Crime Stoppers.