One man is fighting for his life and another is seriously injured after several crashes involving about 30 vehicles caused traffic chaos north-west of Melbourne.

The multivehicle crash on the Western Freeway at Myrniong, near Bacchus Marsh, happened just before 4pm on Monday.

Victoria Police said 14 vehicles were involved in one crash that happened with heavy fog in the area. There were also five other crashes in the surrounding area.

Ambulance Victoria confirmed paramedics responded to “several multivehicle incidents” at Myrniong, with a total of 20 patients taken to hospital.

Police said the cause of the collisions appeared to be heavy fog in the area and drivers not driving to the conditions.

A second day of foggy conditions in and around Melbourne also caused chaos with air travel.

Thick fog blanketed the Melbourne skyline on Tuesday, after similar weather on Monday led to the cancellation of 105 domestic flights. Melbourne Airport communications head Andrew Lund said more were delayed on Tuesday, in what had been an “ugly” 24 hours for the airport.

“It was pretty messy,” he told Melbourne’s 3AW.

Lund urged travellers to check with their airline before heading to the airport.

“Air traffic control needs to put more space between the aircraft for safety, which means we can’t get as many flights through the runway as we usually would and that will then cascade into delays in departures as well,” he told the ABC.

“If the fog does linger, then there may well be delays as the day goes on, so just double check with your airline before heading to the airport – just to see when your flight is due to go out.”

There was also more fog on the stretch of the freeway between Melton and Ballarat where Monday’s crashes occurred. Speed was reduced to 60km/h when the freeway reopened after the police investigation.

On the other side of Melbourne, outbound lanes of the Princes Highway in Oakleigh East were closed after a fatal collision early on Tuesday.

-with AAP