Melbourne's temperature has plummeted by eight degrees in 15 minutes, bringing relief to the city after a stinking hot night and a sweltering morning.
The city reached a maximum of 36 degrees at 2.02pm, and by 2.17pm had dropped to 27.7 degrees, Bureau of Meteorology senior forecaster Keris Arndt said.
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Victoria, Melbourne set to swelter on Thursday
Northern parts of that state are in for the hottest conditions this week, with Mildura expected to get two days of 44 degrees on Thursday and Friday, dropping to 42 degrees on Saturday.
At 4.30pm the mercury in the CBD had dropped again, just under 23 degrees, and was continuing to decline.
"We'll still see it shave a couple more degrees off, but not by much," he said. "It will get a little cooler tonight, down to 20 degrees.
"Still a warm night, but much cooler than last night."
The hottest temperature in Melbourne was 37 degrees, recorded at Essendon Airport.
Emergency authorities have confirmed that five children were rescued from unattended vehicles today, as the state was hit by extreme heat.
Paul Holman, director of emergency management for Ambulance Victoria, expressed frustration and disappointment at the number of children left alone in cars.
![Cooling down at St Kilda beach after another hot Melbourne night.](/web/20170209220613im_/http://www.theage.com.au/content/dam/images/g/u/8/q/q/b/image.related.articleLeadwide.620x349.gu8qif.png/1486620849829.jpg)
"Do not leave your children in cars. I cannot believe that five children were left in cars in extreme heat like today," he said.
"None of those children required hospitalisation, but it is only a matter of time. And it's only a matter of time, if people do not heed this warning, that I'll be standing up here talking about a tragedy. We don't want to do that. This is a community responsibility," he said.
![Melbourne is expected to cool down after 2pm on Thursday.](/web/20170209220613im_/http://www.theage.com.au/content/dam/images/g/l/q/p/j/i/image.related.articleLeadwide.620x349.gu8qif.png/1486620849829.jpg)
Emergency authorities also revealed that 10 children were pulled from hot cars by emergency authorities on Wednesday.
Meanwhile, the CFA confirmed that there had been 40 fires across Victoria on Thursday.
In the southern suburbs the mercury is dropping gradually. And in Geelong it's dropped down to 23 degrees.
Wednesday night was one of the hottest on record.
Hot winds kept Melbourne's overnight temperature at 30 degrees and above for most of the night.
Mildura, on Wednesday night, had the warmest February minimum on record with 30.6 degrees, Ms Yeo said. Melbourne has twice had the same 30.6 degree overnight minimum, once in 2010 and also in 1902.
Senior meteorologist Claire Yeo from the Bureau of Meteorology's extreme weather desk said earlier that the change would be weak and slow moving.
"We are going to see relief in the southern suburbs in the early part of this afternoon, but because the change is quite slow moving and is not a very strong change, we are not going to see the relief in northern parts of Victoria, or even the northern suburbs of Melbourne, until late in the day," Ms Yeo said.
The change that will breathe into the northern suburbs between mid-afternoon and 5pm is expected to be so weak it will not push across the Great Dividing Range, keeping temperatures high in the north of the state with warm overnight temperatures.
Heat health warnings are issued for all northern sections of the state, including East Gippsland, Mallee, North Central, Northern Country, North East and Wimmera regions.
The temperature only dipped below 30 at 3.30am, to 29.9 degrees. The mercury continued to dribble down. At 7am it was still 27 degrees.
It was the hottest night in a month, with January 8 having had overnight temperatures hovering above 28 degrees.
"It was very hot and uncomfortable, and added into that mix is the humidity," Ms Yeo said.
Approaching wind change seen on Doppler. Expected 1-2pm in #MelbCity but it will take a while to cool down! 😓 https://t.co/6NUItVxFQE pic.twitter.com/m4mAGvmqlj
— BOM Victoria (@BOM_Vic) February 9, 2017
"Although we are used to quite warm temperatures through summer we are not used to these kinds of humid conditions in Victoria," she said.
Ms Yeo said the rainfall over the weekend had taken some of the sting out of fire danger warnings. But with winds up to 70km/h and hot temperatures there were still severe fire danger warnings for the Mallee, Wimmera and Northern Country and very high to high fire danger warnings for the rest of the state.
Despite there being no days over 40 degrees for Melbourne this summer, the statistics have held their own. The mean temperature for January historically is 26 degrees, and the mean for this January held at 26.5 degrees.
Stormwater from rains on Sunday and Monday flushed into Port Phillip Bay, reducing water quality but the most recent Environment Protection Authority beach report lists all beaches as having good water quality and suitable for swimming.
Me when that cool change hits Melbourne:#MelbWeather pic.twitter.com/6Qr3dsrmBu
— I. H. Laking (@IHLaking) February 9, 2017
Guess the change is here then! #melbweather pic.twitter.com/mY8HpJfbT1
— Chris Binney (@ChrisBinney) February 9, 2017