UPDATE: VICTORIANS have sweltered through the hottest November day in more than a century, hitting 45C-plus in some areas.

According to weather websites, Mildura's temperature reached 44.5 degrees at 1.30pm.

If it becomes official, that would equal the hottest spring day in Victorian history.

The unseasonal late spring weather was due to the arrival of northerly winds which have coincided with the build up of hot weather in the inland.

Mallee schools and nursing homes have been applying extreme heat policies for today's scorcher.

Some parents of young students have been able to pick up their children and other students offered "modified classes''.

Tonight's Mildura harness race meeting will start at 7.30pm rather than 6.30pm to try and miss the worst of the heat.

 Total fire bans have been enforced in the Wimmera and Mallee regions, with north-western Victoria expected to record the highest temperatures of the day.

The East Gippsland region will be slightly cooler today, with the mercury set to reach a top of 34C in Bairnsdale.

Bureau of Meteorology senior forecaster Dean Stewart said similar weather is to be expected in the coming months.

"It is a bit unusual to see these temperatures in late spring but we've seen temperatures reach mid-40s in Mildura before,'' he said.

"It's a taste of the hot summer to come.''

Isolated showers and thunderstorms are expected to sweep across Victoria's west in the later afternoon.

Mr Stewart said a forecast change would not arrive until the early hours of tomorrow, so the temperature would remain in the 30s until then.

"It will only be a relatively weak change in that it's going to increase the humidity," he said.

"The temperature will fall to about 23C in the morning following the change."

Commuters travelling on V/Line services are advised to allow extra travelling time as speed restrictions have been implemented due to extreme heat, according to V/Line spokesperson James Kelly.

"Generally heat speed restrictions only affect the Bendigo, Swan Hill and Echuca lines, however today we are implementing them across almost our entire network,'' Mr Kelly said.

"This is a safety precaution, but is by no means an exact science, if the temperature does not reach the forecasted maximum we do remove them earlier if necessary.''