Fire authorities have carried out only 10 per cent of planned hazard-reduction burns across NSW as they rush to prepare for a hot, dry summer.

Thick smoke shrouded much of Sydney and its surrounds on Wednesday morning, the third straight day of poor air conditions over much of the state capital.

Air quality was rated as extremely poor at Camden in the city’s south-west overnight, and was still classed as very poor later in the morning.

Conditions were also poor elsewhere in the south-west region and across a swathe of Sydney’s inner west and south, and in the eastern suburbs.

NSW Rural Fire Service Commissioner Rob Rogers said authorities had completed only 30,000 hectares out of a planned 300,000 hectares of hazard reduction burns for the year and they were trying to make up for lost time.

“We are so far behind, we have to take advantage now that we’re in this drying period,” he told ABC TV.

“We’re seeing fire seasons predicted to be a lot more active than they have been for the last couple of years, so we really need to get in and do this work.”

Mr Rogers added that not all of the burning would be finished ahead of the peak fire season. Some would need to be done in late summer, if conditions allowed.

“As conditions warm up, the window to do those burns safely starts to narrow,” he said.

“You’ll see as we start to get to mid-spring and heading towards summer there will be less and less of these burns just because we’ll be worried about being able to contain them.”

Fire authorities have been playing catch-up after managing to complete only about a quarter of planned burns in 2022/23 because of wet weather along the eastern seaboard.

Temperatures are expected to soar later in the week, with forecast maximums in the low- to mid-30s for much of NSW.

Bureau of Meteorology senior forecaster Dean Narramore said a high-pressure system over the state’s east meant there had been little to no wind to blow the smoke away.

He said Sydney residents could expect another smoky night on Wednesday into Thursday morning.

– AAP