Australia Weather News
Temperatures across Australia will soar as much as 15 degrees Celsius above average during the coming days, threatening October records across multiple states and territories.
The unusually intense mid-spring heat sent Adelaide and Melbourne suburbs above 30C on Thursday.
It should lift Western Sydney's maximums to 34C on Friday and 37C on Monday.
Canberra is forecast to reach 33C on Monday, challenging the capital's October record of 32.7C from 1946.
The nation's interior faces several days of oppressive maximums in the mid-40s.
Unseasonable temperatures have lasted for weeks along the eastern seaboard — with Sydney, and possibly Brisbane, on track to observe their warmest October on record.
42C to 46C across four states and the NT
A hot air mass has been building over north-west Australia all month, culminating in highs up to 44C in the Pilbara — just 3C off the all-time national record for October.
An initial burst of hot winds arriving from northern WA has reached NSW after spreading through SA and Victoria on Thursday.
Weather will undoubtedly be a chief talking point around Sydney on Friday as it approaches its warmest October day in two years.
Thunderstorms are also possible in the afternoon, which could include a dangerous supercell storm with large hail and damaging winds, along with a late southerly buster.
However, for most of Australia, even hotter temperatures are forecast.
A second wave of northerly winds will engulf eastern WA on Saturday and then sweep across SA and Victoria on Sunday.
For inland towns of SA, maximums are likely to reach the mid-40s, placing the state's all-time October record of 45.4C under serious threat.
By Monday, the hot, dry air mass will reach the east, sending maximums to near 40C across inland NSW while south-west Queensland soars up to 45C — also challenging the state's current October record of 45.1C.
Hottest forecast for each state/territory, and current October record
Fire threat builds
This week's hot spell is being accompanied by gusty winds and low humidity — a recipe for widespread elevated fire dangers.
Winds are not expected to be strong enough for "extreme" fire dangers across southern Australia, however, a large portion of the country is forecast to experience a "high" danger.
When the fire danger is rated as "extreme", fires will spread quickly and become difficult to control.
A "high" danger only indicates the potential for dangerous fires.
However, the fire threat could be enhanced by dry lightning, a phenomenon where high-based thunderstorms provide the spark to ignite fires, but without rainfall to dampen their spread.
Dry lightning is possible in western SA on Sunday, followed by eastern SA and western NSW on Monday.
Cool change to bring relief
Spells of hot north-westerly winds across southern states are inevitably followed by a cool change.
After Friday's southerly buster on the NSW coast, the second burst of heat will also be tempered by a southerly — dropping temperatures by as much as 15C in 24 hours.
The cool change will reach Adelaide on Sunday evening, Melbourne on Monday, and Sydney on Tuesday where again the southerly has the potential to reach buster criteria.
The cooler air will then gradually filter north into the central interior and southern Queensland mid-week.
Warmest October on record
For much of Australia's east, the hot spell is a continuation of a trend that became established in September.
It has been so warm this month, daytime temperatures from central Queensland to the NSW South Coast are reminiscent of summer, averaging as much as 5C above average.
[core]Through the past 166 years, Sydney's average October maximum at Observatory Hill is 22.2C, with a record mean of 26.2C from 1988.
So far this month, temperatures are running at 27.2C — which is higher than the mid-summer average.
With further hot days ahead, it will take mini-ice age for Sydney not to record its warmest October on record.
Brisbane's weather station has 138 years of data, and its warmest October mean of 28.8C from 2013 is also under threat with a running average of 28.9C so far this month.
ABC