The region will get its first taste of summer a few days ahead of schedule when severe heatwave conditions and heightened pollen levels hit the ACT and south-east NSW later this week.
Daytime and overnight temperatures are expected to be 10 to 16 degrees above average for this time of the year, reaching into the high-30s or mid-40s during the day for many locations from today (26 November).
The Bureau of Meteorology said severe heatwave conditions are forecast to continue through to the weekend from a high-pressure system which is building over the Tasman Sea. This pattern will allow heat to build from Thursday through to the official start of summer on Tuesday next week.
Bureau meteorologist Helen Reid said conditions are also likely to see the first significant risk of fires during the weekend, with dry north-westerly winds.
“The weekend will have a hot, dry summer feel and will also be quite windy, so we’ll be keeping fire dangers and possible fire weather warnings across parts of the state,” Ms Reid said.
She said the hottest temperatures will be felt in the north-west of NSW where the mercury will climb into the mid-40s, while temperatures in the low-40s may also be felt in some coastal areas along the north-east of NSW.
In Canberra and the surrounding region, temperatures will be hot but not extreme. The maximum temperature is forecast to reach 34 on Saturday and 33 on Sunday, while only dropping to just below 20 degrees overnight. Similar conditions will be felt in Goulburn and Cooma.
Further west in Young, the maximum temperature on Saturday and Sunday will nudge 40 degrees.
Along the south coast at Batemans Bay, it will reach 37 on Saturday and 34 on Sunday.
A cooler change is forecast to pass through the area next Wednesday (2 December).
Ms Reid said a heatwave is generally three days or more of warm to hot temperatures that don’t cool very much overnight.
“We do have the imminent arrival of summer and while the calendar does not yet say summer, the end of November is going to be warm and it is going to be felt right across eastern Australia.
“Temperatures will climb into the mid-40s for vast swathes of the western part of the state and even the low 40s for some of the coastal areas, so be warned to have lots of water and lots of shade available, particularly on the weekend and into the beginning of the new week,” she said.
The pollen count is also forecast to be high in Canberra as conditions heat up.
The Canberra Grass Pollen Forecast is rated high for Friday and Saturday and moderate for Sunday, though these ratings may change. The website measures the amount of grass pollen per cubic metre, with between 50-100 particles making for a high rating.
A pollen count above 100 is extreme and on Monday this week, Canberra had record grass pollen count for spring of 193 grass grains per cubic metre.
While rain briefly suppressed the pollen count, it is expected to elevate again with the heat and warm winds, making conditions difficult for hayfever and asthma sufferers.
Meanwhile, the BOM this week forecast the La Niña weather pattern to continue to at least February 2021.