The man was in a truck that rolled onto its side in extreme winds near the Green Valley fire near Jingellic, east of Albury, on Monday evening.

Two male colleagues suffered burns and were taken to hospital.

"Just heartbreaking," NSW Premier Gladys Berejiklian tweeted.

"Words fail at times like this."

The fire, which is also threatening communities on the Victorian side of the Murray River, was one of three NSW blazes subject to emergency warnings on Monday evening.

Another five were subject to watch-and-act alerts, including the massive Currowan fire's western flank dubbed the Charleys Forest blaze.

Looking at smoke plumes from his window, boarding kennel operator Matthew Knight said he was preparing to evacuate for the third time this season.

"We're all girding our loins for tomorrow because it doesn't look good," the Rovers Retreat manager told AAP on Monday evening.

"It's not easy to find somewhere to keep 30 dogs overnight but our priority is the dogs."

The Charleys Forest blaze earlier passed over homes west of Nerriga while those evacuation messages were sent to those near fires in Wyndham near Bega, Jingellic near Corryong and Ellerslie near Adelong.

Those living north of Bemboka - where a handful of homes were destroyed in the 2018 winter fires - were urged to flee to Bega due to a fast-moving bushfire.

Meanwhile, Sydney will experience severe fire danger, with strong dry winds and temperatures climbing to 33C. Parts of western Sydney will surpass 40C.

Extreme fire danger is forecast for the Southern Ranges, Illawarra and ACT while surrounding regions - including the central rangers and the far south coast - are in for severe fire danger.

Total fire bans are also in place for large chunks of eastern and southern NSW, as well as the northern slopes.

Bureau of Meteorology NSW manager Jane Golding said the heat over inland areas would on Tuesday move eastward towards coastal areas.

A temperature inversion - in which warm air overlays cooler air in the atmosphere - will also trap smoke around the Sydney basin, lowering air quality.

Air pollution was on Monday hazardous in northwest and southwest Sydney and is likely to remain so until Tuesday afternoon.

"The area around Goulburn, heading into the coast, (is) an area we're monitoring closely at the moment," Ms Golding told reporters on Monday.

"That's the area the winds will be strongest, and there's a gap in the ranges, they funnel through that area."

She said if the smoke over Sydney was thick enough, it would stop the temperatures from climbing too high and increasing the fire danger.

Conditions would not ease until a southerly blows through on Tuesday afternoon before things re-escalate over the weekend.

The RFS earlier confirmed at least 911 homes had been destroyed in NSW since July 1.

More than 350 homes around the state have suffered some damage, while 72 facilities and more than 2000 outbuildings have been destroyed.

Those with plans to travel through or stay in bushfire-prone areas have been advised to assess the risk and potentially revise their plans.

Australian Associated Press