The Bureau of Meteorology is predicting Victorians can expect some relief from the stifling heat affecting Victoria, by mid-afternoon on Friday.
A high-pressure system, east of Tasmania, and one over the Tasman Sea were expected to merge late on Thursday, causing the hot conditions.
That system was expected to bring fresh, to gusty, northerly winds, before a milder, squally change reached the south-west on Friday morning and central areas by mid-afternoon.
Bureau of Meteorology senior forecaster Richard Carlyon said temperatures would remain high, in many parts of Victoria, overnight.
“We’ll see extreme heat, across the state, on Friday,” Mr Carlyon said.
“We saw some records broken earlier this month, but it will be even hotter again, as we see temperatures move into the 40’s, fairly early in the day and by late morning.
We saw some records broken earlier this month, but it will be even hotter again, as we see temperatures move into the 40’s, fairly early in the day and by late morning.
"With the northerly wind developing, overnight, that means that heat will remain, for many areas across the state we will see temperatures in the 30's overnight."
The temperature will steadily rise, as the northerly wind increases.
Temperatures were expected to reach 46 degrees, in some parts of the north-west.
But a wind change, expected to pass through the state on Friday afternoon, would see temperatures plummet in a very short time.
He said Melbourne would experience a 15-degree drop in temperature, in the space of about 20 minutes, following the passage of the cool change.
“The main impact of the change will be in southern Victoria," Mr Carlyon said.
The drop would be less evident in the north, with the temperature falling from the mid 40’s to the high 30’s.
"They will probably notice a six to eight-degree drop, but it's still quite warm when you think of it dropping from the mid 40's to the high 30's."
The southerly change wasn’t expected to reach the east, until night.
Isolated showers and thunderstorms were also possible over central and northern districts, near the change.
Humidity would also remain high.
Over the weekend, the weather would settle, as the front moved to the east and a high-pressure ridge moved in.
"We have seen that humidity building up over the past few days, there are some good and bad aspects from that.
“Fire danger will be elevated, and we are expecting severe to extreme fire danger, right throughout Victoria.”