A “quirk” of the weather combined with geography will spare residents of Sydney and regions along the NSW coast from the scorching temperatures searing much of the country.
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Sydney and centres such as Newcastle and Wollongong will barely reach 30 degrees over the next week while most other state capitals face days of blistering heat closer to 40 degrees or higher between now and Monday.
National records, including the highest average temperature of 40.17 degrees hit on December 21, 1972, may tumble in coming days as the massive heatwave covers most of the continent. The all-time record of 50.7 degrees at Oodnadatta Airport in South Australia on January 2, 1960, may also be challenged.
Unlike earlier hot spells this summer, though, Sydney's mercury will touch 30 degrees on only one day over the coming week – on Tuesday – according to the weather bureau's latest forecasts.
“It's basically just a quirk of the way the weather system has moved through the region,” said Karl Braganza, the bureau's manager of climate monitoring. “Sydney could quite easily have had a few days of extreme heat but it rarely gets such a long sequence as other places.”
In this case, a large high-pressure system over the Tasman Sea is bringing cooler maritime air over eastern parts of NSW, sparing the region from the blistering continental air flows that have been building up over central parts of Australia.
“The physical set-up, with the mountains to the west and no great land mass to the direct north ... means it's a little harder for the same systems bringing heat to the southern coast to also bring heat to the east coast,” Dr Braganza said. “They therefore have a more maritime climate during these episodes.”
“In this instance over the next few days, the same system bringing warm northerlies to south-eastern Australia is bringing more maritime air over the Sydney region,” he said.
During summer, temperatures in the high 30s or 40s are much less common in Sydney and Brisbane than they are in Perth, Adelaide and Melbourne.
“Residents can be thankful for that, since the maritime climate of Sydney and Brisbane means it is generally humid as well, greatly increasing the discomfort factor, rather than the dry desert-baked heat in the southern capitals,” Dr Braganza said.
Adelaide is heading for 44 degrees today, Melbourne 41, Hobart 39 and Canberra 37, according the bureau's latest forecasts.
