Melbourne faces 10-day heatwave
Day or night, it's going to be warm for a while yet.
Melbourne is likely to swelter through as many as 10 consecutive days with temperatures of at least 30 degrees as a slow-moving high pressure system directs warm winds over the state.
If the heatwave persists as forecast, the run of hot days would smash the previous record hot spell for any month by two days.
There will also be little relief for the city at night, with minimum temperatures expected to remain above 20 degrees for every day except Saturday.
“That's a feature of how warm these air masses have been,” said Karl Braganza, head of climate monitoring at the weather bureau. The average long-term minimum for March is 14.1 degrees.
Temperatures are also likely to climb towards the end of the heatwave, with 36 or 37 degrees predicted for each of the first three days of next week before the arrival of cooler conditions.
The forecast north-easterly winds mean extreme heat will probably be avoided but the added moisture will also have its downside. “The humidity will add to the discomfort,” said Brett Dutschke, senior meteorologist at Weatherzone.
It's the fourth time since November that a so-called blocking high-pressure system has set in over the Tasman Sea, steering hot continental winds over south-eastern Australia.
"The monsoon has been patchy - and certainly we are in rainfall deficiencies over much of the inland region - so (the system has been) dragging down air that is quite warm for this time of year," Dr Braganza said.
"This extends the record warmth from last September...(with) little in the way of cold outbreaks that break up the patterns," Dr Braganza said.
Australia's December-February period was the hottest since records were standardised in 1910, with the average daytime maximum of 35.7 degrees beating the previous high set in 1982/83 by 0.2 degrees, the bureau said last week.
The Climate Commission earlier this week released a report, The Angry Summer, arguing that "all weather, including extreme events, is influenced by climate change."
Friday may come closest to breaking the chain of 30-plus degree days, with sea breezes potentially limiting the daily maximum to the high 20s, Weatherzone's Dr Dutschke said.
Adelaide may endure a longer heatwave than Melbourne, with the city heading towards 12 or 13 days of 30-plus degrees, he said. The South Australian capital, though, is used to March heat, with 15 consecutive days of 35 degrees or more in 2008.
South-eastern Australia may be spared worse heat by tropical cyclone Sandra, now forming off Queensland.
"It's keeping the extreme heat away for a large part of the hotspell but it is helping with (extending) its duration," Dr Dutschke said.
Melbourne's longest stint of 30-degree days in March stands at seven. The city has had four stretches of eight days of such heat since 1890, with the most recent endured in February 1961.
Extended dry conditions have accompanied the scorching conditions across much of southern Australia. The bureau is expected to update its rainfall deficiencies report on Thursday, showing dry regions are expanding.