They'd be right and they'd be wrong.

According to the Bureau of Meteorology senior forecaster Scott Williams, July is shaping up to be the coldest in 20 years.

But, he said, the warmer winters of the recent past were an aberration caused by climate change.

"The fact is that this July isn't exceptionally cold when you look at the longer-term history, back over the last century," Mr Williams said.

"But it is cold relative to the last 20 years, when we have had generally milder winters than the long-term average."

Mr Williams said there were two reasons behind the warming up of the CBD in particular.

"We know that there is an element of climate change or warming, that's in the order of 1 degrees since 1950 across Victoria," he said.

"But probably the biggest factor behind Melbourne being warmer is the huge build-up in the size of the city and the activity of the city.

"The city has grown rapidly in the last few decades. There is heating and cars and everything stirring up air, so it doesn't get that cold at night."

Except for that "persistent south-westerly wind" that we have had this month.

Mr Williams said the change in conditions this July was due to a series of deep low pressure systems in the Tasman and cold fronts pushing through Victoria.

"At this stage, if the current statistics shape up, the average maximum of 13.3C will be the coldest since 1995," Mr Williams said.

"The minimum temperature, an average of 6.8C, is looking like being the coldest for about eight years."

And with a minimum of 8.6C and a top of 12C on Thursday, it is not going to let up anytime soon either.

"Hold on to your hats today. It is going to be a very windy day," Mr Williams said.

"We have already had gusts at Melbourne Airport of 89km/h and we are going to be windy right across central Victoria and the higher parts of eastern Victoria due to the approach of the cold front."

He said the cold front would come through Melbourne at about 9pm on Thursday night, producing "a band of showers of five millimetres of rainfall".

However, those suffering from vitamin D withdrawal will have to make the most of Friday's sunshine, as it will be followed by at least five days of vintage July weather.

"Tomorrow is probably the nicest day, with showery conditions through the weekend and early part of next week," Mr Williams said.

"There will be a bit of sunshine. Following the front the winds will be light, it will get a couple of degrees warmer, with a top of 14 and minimum 5C."

Next week, Mr Williams said, showers were expected every day until Wednesday.

"It is actually even a bit colder than what we have seen this week," he said.

"There will be showers, a cold front Sunday night into Monday, and there will be ... south-westerly winds. And that won't ease off until Wednesday.

"It will be fairly cold weather with a maximum of only 11C expected on Monday and Tuesday."

The south-westerly is expected to ease on Wednesday, but not before Melburnians add another layer to their clothing.