Thursday is predicted to be the coolest day the city has experienced so far this month, and there is no forecast top above 20 degrees until next week.

Even when the warmer temperatures return next week, the nights are expected to remain around 10 to 12 degrees.

Bureau of Meteorology senior forecaster Peter Newham said the change began on Wednesday evening when a "significant cold front" swept in, moving across Melbourne and pushing the temperatures down.

"Just ahead of the front, the temperature was in mid-20s and then it dropped sort of six or eight degrees quite quickly and then it dropped a couple of degrees," Mr Newham said.

"It is going to be cooler for the next four days."

Mr Newham said March weather had been well above average and may well be the warmest on record for much of Victoria.

So the next few days might come as a shock to most except those looking forward to the chill.

"It looks like that warmer period of weather is coming to an end, because we have got, for Melbourne at least, four days in a row forecast to be under 20," he said.

"And there hasn't been a day below 20 degrees this March. The last day below 20 degrees was back towards the end of February."

It is the same all over Victoria, with even some snow predicted for the Alpine region.

On Thursday, Mildura is predicted to be four degrees cooler than on any other day this month.

"It has been well above average temperatures for most March, this cool change will affect the rest of Victoria," Mr Newham said.

"We are forecasting a maximum of 23 degrees for Mildura [on Thursday]. The lowest maximum so far we had this March is 27 degrees, so it is a significant drop.

"We are even forecasting a chance of snow on the peaks of the ranges, most likely around Mount Baw Baw."

Melbourne will see a maximum of 18 degrees on Thursday, the coolest day this March, followed by 18 degrees on Friday, 19 degrees on Saturday and 18 degrees again on Sunday.

The nights will be cooler too, with Saturday to see a 10-degree minimum for the first time this month in Melbourne.

If that makes Melburnians shudder they should spare a though for Ballarat, where it's going to be 5 degrees on Friday.

But take heart, the sun will come out again next week.

"It does look like it will warm back up again early next week. So we are back into the mid-20s by Wednesday next week," Mr Newham said.

"The cycle will continue, we will get some warmer periods and then some cooler periods. Obviously, once we are into April, it gets harder and harder to have the really, really warm weather."