The mercury plunged to minus 7.4 degrees at Canberra Airport at 7am, with an apparent temperature of minus 10.4 degrees.

Skiers at Perisher endured an even colder night, with a low of minus 9.2 degrees recorded at 9pm and 9.30pm on Sunday.

Thredbo's low came much earlier in the piece, hitting minus 7 degrees at 5pm on Sunday.

"The reason it was so cold overnight is we had clear skies, light winds and a dry air mass," Bureau of Meteorology duty forecaster Katarina Kovacevic said on Monday morning.

"When those three things combine, it's like the perfect recipe for cold mornings."

The good news is that it's set to be the last time we plunge well below zero for a while in Canberra.

The chilliest temperature forecast for the rest of the week in the capital is just minus 1 degree, with that low expected on Thursday and Friday morning.

"It's going to warm up because it'll be windy and cloudy, and clouds kind of act like a blanket overnight," Ms Kovacevic said.

"We're going for a low of zero [overnight into Tuesday]."

The bureau's forecast shows just a 20 per cent chance of rain every day until Thursday.

That will change at the end of the week, with an 80 per cent chance of showers on Friday and Saturday, followed by a 60 per cent chance of rain on Sunday.

As much as 17 millimetres of rain is expected across those three days, in what would be welcome news for farmers as the ACT battles a prolonged dry spell.

Just 3 millimetres of rain has fallen at Canberra Airport so far in July, on the back of 69.6 millimetres between March and June in what was a 14-year low for that time of year in the capital.