Sydney covered in smoke. It’s from a bushfire more than 400km away

Sydney’s air quality plummeted on Tuesday due to smoke from a major bushfire burning more than 400 kilometres away in the state’s north-west.

Air quality in Sydney’s east, north-west and south-west was labelled “poor” on Tuesday afternoon after thick smoke made its way across the city throughout the day.

Sydney was choked by bushfire smoke on Tuesday.Credit: Oscar Colman

At “poor” level, the government recommends people reduce outdoor physical activity and close windows and doors when indoors.

The smoke blew into the city from the Duck Creek bushfire in Pilliga Forest in the Narrabri LGA – a six-hour drive away. The fire began on December 8 and has now burnt more than 120,000 hectares.

The NSW Rural Fire Service said the smoke was expected to lift across Sydney for Wednesday as southerly winds made their way across the state.

“If you have a respiratory condition that could be worsened by smoke, activate your health management plan and seek medical advice if necessary. Take precautions, such as staying indoors and closing windows,” the RFS said on social media.

The fire was raised to emergency level on Monday when it began threatening homes. However, it was lowered on Tuesday afternoon to a “watch and act” level.

That warning was again elevated to emergency level just after 6.30pm on Tuesday as storms moved into the area, creating erratic fire conditions. It was reduced again to “watch and act” before 7.30pm as rainfall assisted the firefighting effort.

The NSW RFS said the Pilliga blaze worsened on Monday due to a fire-generated thunderstorm contributing to “erratic” firefighting conditions.

The fire created a phenomenon known as a pyrocumulonimbus, a weather system contained within the smoke cloud of a large bushfire, the NSW RFS said.

This happens when the intense heat of a fire rises rapidly into a smoke plume and drags cooler air up with it, and as the plume rises and cools in an unstable atmosphere it creates its own thunderstorms.

This bushfire-generated weather system causes dangerous fire behaviour – it can blow the flames in different directions and cause spot fires as embers are blown far ahead of the fire front. Lightning can even develop.

The fire ripped through the Pilliga forest, which is also the site of the proposed Santos Narrabri gas project.

A spokesman for Santos said the fire had not posed a risk to any Santos facilities, but they had shut down operations.

“The fires in the Pilliga are of enormous concern to our community around Narrabri. Santos is working very closely with the Rural Fire Service and the Forestry Corporation,” the spokesman said.

“We are offering our full support to the response effort, including access to our water tanks and the use of our facilities as safe refuge for firefighting crews if needed.”

As of 6pm, there were 76 fires burning across the state, with 27 not yet contained. More than 600 firefighters and incident management personnel are on the ground across NSW.

For the rest of the week, showers and cooler weather are predicted, with Sydney set to stay in the mid to high 20s in the lead-up to Christmas.

Christmas Day will be mostly cloudy, with possible showers and storms for most of coastal NSW, including Sydney.

The Bureau of Meteorology’s official Christmas forecast for Sydney is: “Cloudy, with a high chance of showers. South-easterly winds of 15 to 25 kilometres per hour. A minimum temperature of 19 degrees and maximum temperature of 26 degrees.”

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