There was an unusual meteorological occurrence in the dead of the Canberra night last night, and almost everybody in a city under Covid lockdown would have slept right through it.

• Between 1:40 am and 1:50 am, the temperature skyrocketed suddenly from 4.5°C to 10.2°C.
• That's a 5.7°C rise within 10 minutes. In the dead of a Canberra winter night!
• By 2:40 am it was 13.3°C . That's a 8.8°C rise in an hour. Again, in the dead of a Canberra night!

You can see the dramatic and sudden temperature shift illustrated really well on our Canberra observations page, on which you'll find the graph below. The red line is the key indicator.

But why did it happen?

Canberra, as we all know, is cold by Australian standards at this time of year, especially at night.

• The average August minimum is 0.9°C.
• You expect temps to dip below zero on around 13 nights each August.
• There have been 10 subzero nights so far this August, which is in the normal range with just over a week to go.

Last night's minimum was 3.9°C at 12:56 am. When a night stays windless, allowing heat to radiate into space, you'd generally expect to lose several more degrees in the wee hours of the night before the sun starts to warm the atmosphere at ground-level around 7 or 8 am.

But right on about 1:40 am, the wind picked up significantly, as you can see on the graph below, which you'll also find on our Canberra observations page.

The surge in wind, ahead of a cold front crossing SE Australia, mixed warmer air which was sitting above the city (in what's called a temperature inversion) with the cooler air at ground level.

As Weatherzone meteorologist Esteban Abellan told you this weekend, there's been a lot of summery weather around SE Australia in the last couple of days.

• Melbourne had its highest temp of winter 2021 yesterday, with a top of 22.2°C, which the late great cricketer commentator Richie Benaud would have enjoyed.
• Meanwhile Sydney is heading for 27°C today, ahead of a change tonight with some significant and possibly very heavy rain on the way on Tuesday.

There's also plenty of cold air on the way. Melbourne is already feeling it, with a top of just 14°C on the cards for Monday, while snow has already started falling on the Victorian alps and is making its way north to the NSW snowfields.

Sadly, the ski resorts remain inaccessible to snow-lovers due to Covid lockdowns in NSW and Victoria.