Although every winter seems colder than the last, there were times that this one actually lived up to the billing.

We didn't get off to a good start, with the temperature on July 1 – a bracing minus 8.7C - the coldest in Canberra for six years.

By mid-July meteorologists had declared that Canberra was in the throes of its coldest start to winter in more than three decades.

Although most will rejoice with the official arrival of spring, residents should not be rushing to switch off their heaters just yet.

"Canberra is looking sunny for the next couple of days," said meteorologist Ash Lange from the Bureau of Meteorology.

"But it will still be quite cold with a frost around."

Don't bank on clear blue skies to start the season either, Ms Lange said.

The smoke that lingered on Thursday came from a hazard reduction burn in Kowen, to Canberra's east.

Bureau of Meteorology duty forecaster Rob Taggart said cold temperatures had trapped the smoke.

"If [the cold air] rises just a bit above the surface and it moves into a warm layer then it can't rise any further because it's colder than the air above it," Mr Taggart said.

ACT Parks conducted a hazard reduction burn at the Kowen Forest, north east of Queanbeyan, on Tuesday.

ACT Parks Fire Forest Roads senior manager Neil Cooper said 95 per cent of the burn was now completed.

"There will be crews out there today cleaning up one or two piles that didn't burn," Mr Cooper said.

"It's breaking up that fuel across the landscape."

Mr Cooper said Tuesday's burn was only 150 hectares and they planned to conduct 8000 hectares between now and next winter.

"People in the ACT probably need to get used to experiencing a small amount of smoke," Mr Cooper said.

Mr Cooper said the haze over Canberra on Wednesday was thanks to unexpected wind conditions which pushed the smoke across the capital.

Anyone with health issues that may be exacerbated by the smoke could register at environment.act.gov.au to register for warnings before future burn offs, he added.

He said firefighters had a limited time frame and conditions to when they could conduct burn offs so as not to disrupt air traffic, hospitals or even vineyards.

"We are conscious of smoke and we are trying to minimise the impact of smoke on the community," Mr Cooper said.

ACT Health said they were monitoring the situation with NSW Health.