Melbourne has been issued with a severe thunderstorm warning by the Bureau of Meteorology for at least the next hour.
The thunderstorms were detected at 3.45pm and are due to sweep across the city, said the Bureau. Damaging winds are likely, with a wind gust of 90km/h already observed at Laverton.
The State Emergency Service is warning people to keep clear of fallen power lines, stay indoors if possible, avoid using the telephone, avoid sheltering under trees and switch off computers and electrical appliances.
Another thunderstorm warning may be issued by 4:55 pm.
A more general severe thunderstorm warning is also current for the Central, Mallee, North Central, West and South Gippsland, Wimmera and parts of the South West and Northern Country districts.
♦ Tough to get to sleep last night? Tossed and turned? Chances are that you're not alone.
Melbourne's minimum temperature overnight was 23.9 degrees at 3.30am, the Bureau of Meteorology reported - making it the hottest December night in nine years.
And it took quite a while to get there. At 10pm, it was still 30 degrees - the city reached its top of 34 degrees at 5.30pm.
In Melbourne's west, the temperature was a little cooler. In Laverton, the temperature dropped to 20 degrees at 3am, and dropped just below that at 6.30am.
On the other side of the bay, Frankston's lowest temperature was 21.6 degrees, recorded at 3am, and it dropped to 21.3 degrees in Scoresby at 1am.
It was worse still for some, with even the possibility of air-conditioning ruled out.
A section of Bentleigh was without power from 1am after a possum caused a high-voltage line to connect with a low-voltage line in Loranne Street, resulting in a power surge, United Energy spokesman Stuart Allott said.
‘‘We are investigating how it happened but it didn’t end well for the possum,’’ he said.
He said power surges were not common but stormy weather in Melbourne this year had seen a 30 per cent rise in high and low-voltage power lines connecting and causing a surge on the distributor’s network.
He said workers were inspecting all 50 homes, checking meter boxes and appliances before turning the power on for each property individually. He said customers were able to make a claim for appliance damage as a result of a power surge.
In Brunswick, 1278 homes were without power this morning from 7.40am, after trees hit power lines in Stewart Street. Power was restored at 9am.
Temporary relief from the heat is on the way, but hot and sticky nights are predicted to persist until early next week.
The bureau has forecast a late shower for Thursday and a top of 35 and a minimum of 21. Minimum forecasts are measured between 6pm and 9am.
For Friday, a top of 28 has been forecast, with the possibility of showers.
Storms are expected on Saturday, with a low of 22 and a top of 27 and from Sunday, it's a return to spring-like conditions, so don't put the jumpers away for summer just yet.
The forecast top temperature on Sunday is 21 degrees, with just 19 on Monday and 21 expected on Tuesday.
And the umbrella might be needed on Wednesday, when a possible shower is expected.
With Deborah Gough