Canberra is expecting a top of 28 degrees amid scorching heat in early spring across Australia's southeast.
The NSW RFS has upgraded the fire danger warning for the far south coast to "catastrophic" following stronger than expected winds.
It comes a day after a five hectare grass fire near Nass Road, Booth in southern ACT. Crews from ACT Fire & Rescue extinguished the fire at about 5pm.
The Bureau of Meteorology's Jake Phillips said it's looking like bushfire threat is greater than it has been for the last couple of years.
"Fortunately the environment is not quite as dry as it was in 2019 [so] we're not expecting anything of that magnitude, but its definitely a situation that people need to be aware of."
Twenty South Coast schools will keep the doors closed on Tuesday amid concerns about extreme heat and windy conditions.
Bodalla Public School, Mogo Public School, Broulee Public School, St Bernard's Primary School, Batemans Bay Public School, Sunshine Bay Public School and Narooma High School have indicated schoolwide closures following Rural Fire Service advice of an extreme fire danger rating through the day.
Temperatures in Canberra are expected to dip tomorrow with a forecast of 23 degrees.
Temperatures are forecast to be in the high teens on Thursday and Friday. A cold front trying to move over the ACT and NSW has been blocked by a slow moving high pressure system over the Tasman Sea.
The front should reach Canberra around Wednesday. Mr Phillips said it was not unusual for spring to have inconsistent weather.
"It's a very variable time of year, September and even October [so] people can expect [the weather] to fluctuate," he said.
The ACT has an average fire potential this summer, ACT Rural Fire Service chief officer Rohan Scott has said.
"We are constantly monitoring the risk that is available, and we're trying to mitigate any of those potential fire runs as we can," Mr Scott said.
The ESA is encouraging Canberrans to download a bushfire, flood and storm emergency survival plan to prepare for the fire season.
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