Severe heatwave weather warning in place for eastern NSW as temperatures soar up to 12C above average
In short:
A severe heatwave warning is in place across eastern NSW until Thursday as temperatures are predicted to soar up to 12 degrees Celsius above average.
Wednesday is forecast to be the hottest day in Western Sydney, with temperatures reaching 40C.
What's next?
The heatwave will dissipate by Thursday and Friday, with rainy and stormy conditions likely.
A heatwave across eastern New South Wales continues to intensify, sending temperatures up to 12 degrees Celsius above average and prompting a severe weather warning until Thursday.
The temperature is forecast to reach the high 30s in the state's northern and eastern inland on Tuesday, including across Western Sydney where residents will sweat through temperatures of up to 39C — the hottest in spring for four years.
Wednesday will bring even higher temperatures, reaching 40C in Western Sydney and 33C in the CBD. It will be Penrith's fifth consecutive day above 35C — a new record for spring since the weather station commenced operation in 1995.
A heatwave warning has been issued for NSW until Thursday. (Supplied: Christine Harris-Hansell)
Towns in northern parts of the state and the Hunter will also swelter, with maximums in the high 30s predicted during the coming days, including tops of 39C in Bourke, Singleton and Muswellbrook.
While the north-east half of NSW continues to bake into the middle of the week, a band of widespread showers and thunderstorms is gradually creeping across the state's west.
Lake Victoria was already drenched by 63 millimetres in the 48 hours to 9am on Monday — triple the region's November average rain in just two days.
Heatwave to diminish by Thursday and Friday
Bureau of Meteorology forecaster Jonathan Howe said warm temperatures across Australia's inland, southern NT and outback NSW were being dragged to the east coast by an approaching cold front, causing the heat to be funnelled across Sydney.
And while temperatures over the next few days were not going to break "widespread records", they were still above the average expected for this time of the year, he said.
The community have been told the nights will also be warm. (Supplied: Tim Ritchie)
He warned people should also expect some very warm nights, with very little relief until Thursday onwards.
"So we are expecting quite a shift to rainy and stormy conditions heading into the weekend, with the potential for severe thunderstorms as well," he said.
"The rain and storms will help to cool things down a little bit, so we are expecting those heatwave signals to diminish heading into Thursday and Friday.
"Temperatures still remain quite high, though, so 30C on Thursday, 25C on Friday and Saturday, but Sydneysiders will definitely notice the humidity."
Looking ahead into next week, Mr Howe said it would be unsettled, with the humidity persisting.
Penrith is predicted to have its fifth consecutive day of temperatures above 35C on Wednesday. (Supplied: Nepean Rowing Club)
NSW Rural Fire Service Inspector Ben Shepherd described the coming days as the "first significant heatwave of this season", and said while that meant there would be a heightened fire threat, the absence of strong winds lowered the risk.
"What we want people to understand is what the risk means to them. I think many people underestimate the dangers of heatwaves," he said.
"They are a bit of a silent killer, and we want people to understand what they can do to beat the heat.
"But at the same time, we want people to understand that there will be an increased fire risk, but not what they would typically expect to see."
Blackout risk downgraded
The run of hot weather and the expected surge in electricity usage as people try to cool off prompted the energy market operator to issue a warning on Monday about potential blackouts.
The Australian Energy Market Operator's (AEMO) lack of reserve (LOR) notice for Tuesday until Wednesday afternoon was categorised as LOR3 — the highest tier of risk.
Housing estates like this one in Oran Park in South Western Sydney feature rows of homes with dark roofs. (ABC News)
However by the afternoon, it had been downgraded, with the AEMO saying the forecast electricity reserves had improved.
"The previously forecast Lack of Reserve Level 3 (LOR3) has been downgraded to a less critical Lack of Reserve Level 2 (LOR2)," it said in a statement.
"This improvement is largely due to the cancellation of transmission outages in the region."
On Monday, NSW Premier Chris Minns acknowledged that consecutive days of high temperatures complicated the management of the grid, but reassured the public the government would be "transparent" about the situation.
"We will be as quick as possible with updates to the community about possible interruptions with supply," he said.
"And what members of the public could do if we do have a significant number of high-temperature days in a row."
The powering down of four coal generation units, including one in the state's biggest coal-power plants at Eraring near Lake Macquarie, has also impacted supply.
NSW Premier Chris Minns acknowledged that consecutive days of high temperatures could make it difficult to manage the grid. (ABC News)
The AEMO said the situation would be monitored and if electricity supply forecasts deteriorated it would "take all necessary measures, including the activation of off-market reserves, to ensure supply reliability".
Australia's electricity system operates with a level of extra energy that acts as a buffer during events where there are threats of blackouts.
The AEMO issues a LOR when that reserve reduces, warning that load shedding may be required if market responses are inadequate.