Australia Weather News

Melburnians — and the world's best tennis players — have battled through temperatures of about 42 degrees Celsius, as energy authoritiescurtailedsome industrial users' power consumption and firefighters across Victoria stood on high alert.

In the city's west, Avalon and Laverton reached 42.8C and 42.7C respectively before a cool change came through at about 5:00pm on Friday and brought metropolitan temperatures down by 12C.

Across the state, every forecast district had at least one town reach over the 40C mark, with Walpeup in the Mallee hitting 45.7C and Longerenong in the Wimmera reaching 45.5C.

Ambulance Victoria's Paul Holmansaid the second day of the heatwave was one of the hottest in over two years in Melbourne, and he defended authorities' weather warnings over the past two days.

"There has been some commentary, certainly in the last 36 hours, where people are saying we're overreacting to this heat and it's just a couple of hot days in Melbourne," he said.

"What the commentators don't see is what we see in ambulances and what we see every time there's a hot day and every time there's an extreme hot day.

"That is the vulnerable in our community who, in actual fact, die as a result of this heat. Heat kills."

He said while Friday had been a "normal workload" for emergency services, Thursday had seen 31 cardiac arrests.

"Our messaging is, first and foremost, to go out and look after those vulnerable people in our community," he said.

"We're going to continue to do that, and we're going to do it very hard because this is about saving lives."

Earlier Emergency Management Commissioner Craig Lapsley called on the community to take caution in the heat after nine children — all under the age of five — were found left in hot cars on Thursday.

System 'working' to beat fires

Friday afternoon's cool change saw the mercury drop to around 27C in metropolitan areas.

But Mr Lapsley said northern Victorians were unlikely to get respite from the change.

"However the change does not extend to the northern part of Victoria, and northern Victoria will remain hot overnight, tomorrow, and will continue over the weekend to reach into the 40 degrees," he said.

Mr Lapsley said authorities managed to put out all fires that were burning on Thursday, including a grass fire near Colac, which destroyed two houses, described as derelict homes, and some livestock and fences.

"Since then, we've seen the Mount Misery fire, which is west of Ballarat, 140 hectares in size — we used all sorts of aircraft, small helicopters, big helicopters, small fixed-wing, the large air tankers went — and in 90 minutes, we had that fire brought to a level of containment," he said.

"That tells us the system's working, and we've got good capabilities being deployed in Victoria."

A number of other fires are burning across the state, with a Watch and Act message downgraded to advice for a grassfire at Kellalac, in the state's west.

The extreme heat has also caused train services in Melbourne to go slower, with concerns tracks could buckle under the pressure. Passengers have been warned to plan ahead and allow for delays.

On Thursday, temperatures on court at the Australian Open reportedly hit 69C, prompting six-time champion Novak Djokovic to describe conditions as "brutal" and his opponent Gael Monfils to complain he was "dying on the court for 40 minutes".

Industry may need to rein in power use

Meanwhile, the Australian Energy Market Operator (AEMO) has curtailed the energy consumed by some industrial power users, or turned on temporary back-up diesel generators, to shore up Victoria's power grid.

Power providers were told on Thursday night to be on standby to "provide contingency support" under the Reliability and Emergency Reserve Trader (RERT) scheme — a short-term measure put in place to deal with potential electricity shortfalls across Victoria and South Australia this summer.

Alcoa's aluminium smelter at Portland, on Victoria's far south-west coast, confirmed it has been warned it may need to rein in power use on Friday afternoon.

"AEMO has asked Alcoa Portland Aluminium to be on standby this afternoon and AEMO operational control will decide whether this request is activated," a spokesperson for the company said.

"If managed appropriately Portland Smelter can be safely curtailed for short time periods (up to one hour) to provide much needed capacity during peak demand periods."

The RERT was put in place in the wake of the closure of the Hazelwood coal-fired power station in the Latrobe Valley.

Under the RERT scheme, AEMO has contracted 884 megawatts of "demand side response" across Victoria, NSW and South Australia.

This means paying smelters, factories and other heavy power users to rapidly curtail their energy use to rein in demand, when the system is under strain.

"AEMO does not envisage any supply impact to Victorian and South Australian consumers," it said in a statement.

"However with temperatures rising, and the risk of bushfires ever present, AEMO has determined the need to increase its operating reserve by enabling additional resources to be available should market generation reserves deplete."

The RERT scheme also includes the option of accessing 96 megawatts of temporary generators installed in the Latrobe Valley and a further 276 megawatts of diesel generators installed in Adelaide by the South Australian Government.

The tightened supply-demand balance in Victoria became obvious when the Loy Yang B coal unit tripped in extreme temperatures on Thursday afternoon, instantly removing more than 500 megawatts of power from the grid, sending wholesale power prices soaring, and prompting a Level 2 "Lack of Reserve" declaration from the market operator.