After several days of blue skies, smoke haze from nearby bushfires has returned to the capital.
The smoke haze rolled back into Canberra just before 9pm on Sunday and continued to linger well into Monday morning.
The ACT Emergency Services Agency said the smoke haze came from bushfires burning over the border in NSW. Fires are continuing to burn at an advice level near Adaminaby and on the South Coast.
The smoke plume visible across Canberra from the Namadgi fire is expected to hit the urban area about 8pm.
The Monash, Civic and Florey air quality stations recorded the air quality as hazardous at 11am on Monday.
The Emergency Services Agency said firefighters were continuing to patrol the Beard fire in the ACT, which threatened homes and businesses near Oaks Estate and Queanbeyan last week.
"Canberrans are reminded to please call triple zero if you see an unattended fire, not just because you see or smell smoke," a spokesman for the agency said.
Bureau forecaster Helen Kirkup said the smoke haze was driven by easterly winds coming from the bushfire front.
"The winds are blowing from where the fires are, but we expect it to clear on Monday within the next few hours," Ms Kirkup said.
"We'd be looking at the wind shifting to the north-west and that should set in by midday.
"However, we expect the smoke haze will come in again overnight."
Canberra has experienced periodic severe smoke haze since fires sparked in NSW in late November.
The highest index ratings were recorded on New Year's Day, all in Monash, where it peaked at 5185 - more than 25 times above hazardous levels.
An air quality index above 200 is considered to be hazardous.
The return of the smoke haze to the capital comes as heatwave conditions are also expected to return to Canberra later in the week.
Temperatures are forecast to be in the mid 30s for most of the week.
A top of 36 is expected on Tuesday, before highs of 35 and 37 on Wednesday and Thursday respectively.
Canberra is then set to swelter through 40-degree days on Friday and Saturday.
Ms Kirkup said coastal winds would turn to the east later in the day, a pattern that's expected to continue throughout the early part of this week.
"It's not exactly a sea breeze, but the easterly winds push inwards later in the day," she said.
"During the day on Tuesday, in Canberra, the winds will push back to the north-west again."
The bureau has predicted for easterly winds up to 30km/h during the evening on Tuesday and Wednesday.
North-westerly winds that are expected to clear the smoke haze from the capital have been forecast for Friday and into the weekend.