The CBD saw a low of 3.6 degrees a little after 7am, just as most of the city was waking up. That's the coldest it has been since August 4 2015.

Expect worse. Melbourne usually gets its coldest days in late June and early July. Only a month to go!

A jogger runs with her dog around Royal Park in the cold conditions this morning on the last day of autumn. Photo: Vince Caligiuri

The freeze is being caused by the lengthening nights, as we approach the shortest day of the year in three weeks. Less sun means less warmth, which means very cold fingers and toes.

Tuesday night's chill was helped along by a ridge of high pressure that sat over much of Victoria, keeping the skies clear.

While we often think of heavy skies as a sign of bad weather, clouds help keep the warmth in.

Photo: Vince Caligiuri

Melbourne of course wasn't the only part of the state to record a low, with places like Coldstream dropping to -2.3. The mercury in most suburbs hovered about 0 and 1.

Unfortunately, because the skies were clear there was no humidity to form snow on the ski runs.

Expect the temperatures to hover in the mid teens all week, until Sunday hits us with a dose of rain.