Eight people have been rescued after they were trapped in their cars by heavy snow in Victoria's north-east, following an unseasonably heavy dump of snow in the state's alps.

Key points: Four children were among eight people rescued after spending the night trapped in their cars

Four children were among eight people rescued after spending the night trapped in their cars Wednesday is forecast to see the coldest temperatures, most snowfall and strongest winds in a week of cold weather

Wednesday is forecast to see the coldest temperatures, most snowfall and strongest winds in a week of cold weather Resorts say they have been surprised by the weather, but are hoping it means good snow for the start of the season

Four children on camping trips with their fathers spent the night in their vehicles after they got stuck in snow in the Alpine National Park near Mount Hotham.

Police said two four wheel drives from New South Wales became bogged on a gravel track, and another two cars from Victoria became stuck when they stopped to help the other drivers.

They raised the alarm with emergency services around 4:00pm on Monday, but unsafe weather conditions meant they had to wait until around 11:00am on Tuesday to be rescued.

The group, which included children aged between 6 and 12, had food and shelter while they waited out the night in heavy snow.

The families spent the night in their vehicles before being rescued by the SES. ( Supplied: Graham Gales )

Bright SES deputy commander Graham Gales said they were relieved to be rescued.

"They were out well-prepared in terms of their equipment, they had the right vehicle, but they'd been caught by a snow shower that they weren't necessarily ready for," he said.

"They had been camping out for a few nights, so they had food, water, tents."

When they were reached by rescuers, the Victorian group were able to get their vehicles free but police said the NSW drivers did not have the right equipment to travel in the snowy conditions and had to leave their cars behind.

Blizzards have swept through the Victorian Alps for the second day in a row, blanketing parts of the north-east in snow. ( Supplied: Mount Hotham Alpine Resort/Chris Hocking )

Students, teachers rescued during five-day hike

Bright police senior sergeant Doug Incoll said there had been three rescues in the region in 24 hours, including two teachers and eight students who were on the last day of a five-day hike on the Bogong High Plains.

"They woke up yesterday morning and were inundated with snow and blizzard-like conditions," he told Statewide Drive Victoria.

"They weren't in a position to go anywhere. They tried but they had to turn around and they were exhausted.

"It's a timely reminder … people really need to be cognisant of the predicted weather."

Chris Hocking at the Hotham Alpine Resort said 40cm of snow had fallen at the resort since Sunday, and temperatures had dropped to as low as -5 degrees Celsius.

'Fairly unusual' early snowfall

A cold front has swept across the state, bringing snow to areas as low as 700 metres above sea level, including near the central Victorian town of Trentham.

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Ballarat, west of Melbourne, is bracing for its coldest day in two decades, with a maximum temperature of 6C for Wednesday.

"It's not unusual to get snow in May, but it is unusual to get snow to this depth," Bureau of Meteorology senior forecaster Richard Carlyon said.

A severe weather warning was issued for areas from the south-west coast across to the east and north-east of Victoria, with winds expected to reach more than 100 kilometres per hour in the Alpine region overnight.

The strongest cold front is forecast for Wednesday, which Mr Carlyon said would "pack a punch" with wind, temperatures and snowfall as low as 600m.

'Winter has arrived' in snow resorts

The cold front is good news for Victoria's snow resorts ahead of the official snow season, which has its opening weekend from June 8.

"It tells us that winter has arrived, and the snowmakers are adding to it as well. So it's more than likely that we'll have snow for opening weekend," Falls Creek's Deb Howie told ABC Radio Melbourne.

Snow fall has left people jumping for joy at Mount Hotham Alpine Resort, which saw around 20cm of snow overnight. ( Supplied: Mount Hotham Alpine Resort/Chris Hocking )

Ms Howie said this week's weather had caught her and her colleagues by surprise "because we've had such a long, hot summer, and even up until a few days ago we were all in short sleeves".

Mt Hotham's Mr Hocking said based on what he had seen, it "could be the best start to the snow season since the year 2000", when the slopes saw record falls.

The weather bureau's Mr Carlyon agreed, saying while it was normally a struggle to get snow on the ground by the start of the season, it "looks good for the opening weekend".