Sydney weather LIVE updates: City temperatures set to top 40 ...

It was still more than 41 degrees in Penrith and Badgerys Creek well after 6pm as the city eagerly awaits a southerly buster now due to hit the city around 8pm.

Temperatures across most of the city had fallen by about 5 degrees at 6.40pm and at Observatory Hill it was 31.5C.

But in Penrith, they were still suffering with 41.6C and Camden was 39.8C, a full 7 degrees hotter than Sydney Airport at the same time. Gosford has fallen from 41.4C to 30C and Terrey Hills has dropped from 40.7C to 25.7C at 6.18pm.

At 6.40pm the temperature in Yarramundi was still 42 degrees Celsius, hot enough to cook some carp, caught in shallow waters around Yarramundi reserve while people kept their cool in the shallow waters.Credit: Dean Sewell

A total fire ban has been declared for the Northern Riverina and Northern Slopes regions tomorrow, due to forecast hot, dry and windy conditions.

It was still 42 degrees in Penrith at 6.40pm. Credit: Dean Sewell

Smog covered large areas of Sydney today from around 11am reducing the air quality in many parts of the city to a rating of ‘fair’.

NSW government monitoring stations in Randwick, Parramatta, Penrith and Liverpool recorded rising levels of ground-level ozone as the mercury rose sharply.

People enjoying the hot weather on Bondi Beach today.Credit: Flavio Brancaleone

Ozone is one of the main ingredients of smog and is formed by chemical reactions between volatile organic compounds (VOCs) and oxides of nitrogen driven by the amount of UV light and higher temperatures. Its concentrations are higher in summer, and usually reach their maximum in the afternoons and early evenings.

Ozone is a lung irritant, and can worsen asthma.

85 fires are burning across NSW, 38 of which are yet to be contained.

With hot north-westerly winds driving temperatures up across most of the state, fire crews are facing challenging conditions.

A bushfire near Narrabri burning today.Credit: Jen Osborne

A Fire and Rescue NSW spokesman said they “strategically moved” resources out of the centre of Sydney to areas on its outskirts to quickly respond to bush and grass fires if they do occur.

However, there have been no major fires. A small grass fire in Castle Hill was controlled this afternoon.

“We urge people to follow the directions of local authorities and remember there is a total fire ban in place across the state today,” he said.

A total fire ban is in place for the Greater Sydney, Lower Central West Plains, Southern Slopes, Northern Riverina and Central Ranges areas.

For anyone on the water this afternoon the Bureau of Meteorology has issued a gale-force wind warning for Sydney’s enclosed Waters, the Sydney Coast and Illawarra Coast as well as a damaging wind warning for the city with peak gusts over 90 km/h.

Locations on land predicted to be most affected by the wind include Manly, Randwick, Cronulla, Wollongong, Bulli, Port Kembla, Albion Park, Kiama and Huskisson.

The State Emergency Service advises people to move vehicles under cover or away from trees.Secure or put away loose items around your house, yard and balcony.

Keep at least 8 metres away from fallen power lines or objects that may be energised, such as fences.

Sydney concert goers are sweating through a brutally hot day, with temperatures in the 40s, hoping for relief from a cool change sweeping up the east coast.

At least 100,000 people are descending on the entertainment precinct at Homebush where the mercury climbed to 42.5C at 3pm on Saturday afternoon.

US rockers Foo Fighters will play to a huge crowd at Accor Stadium while US rapper 50 Cent is also expected to get thousands of people jumping at his second Sydney show at Qudos Bank Arena, despite the stifling heat.

Thousands more are attending the hard techno dance music festival Epik at the Sydney Showgrounds.

With an earlier start, the dance music fans could miss out on the cool change, but Foo Fighters and 50 Cent fans could be in luck.

The Bureau of Meteorology expected relief to reach the Sydney coast between six and eight pm.

Videos posted to social media show organisers outlining access to cooling station at the Epik event site, with cool water misting fans and numerous water stations set up for patrons.

Epik fans have been urged to keep hydrated.

NSW Health has issued a factsheet urging concertgoers to take a break from dancing if they’re feeling unwell and try to avoid the sun.

It advises fans to take advantage of cool-down stations, and warned the effects of drugs and alcohol are often worsened by extreme heat.

“If you’re dancing, outdoors and or taking MDMA it can be very easy to overheat as the drug interrupts your body’s cooling down mechanism, meaning your body will create more heat than it can get rid of,” the warning read.

Frontier Touring said extra staff had been hired to help assist with first aid stations set up around the stadium.

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Sydneysiders have headed to air-conditioned shopping centres to beat the heat.

Throngs of shoppers were seen dining indoors and browsing the Queen Victoria Building’s boutique storefronts in Sydney’s CBD.

Shoppers escape the heat at QVB, in the Sydney CBD as temperatures soar to mid-40s in the west.Credit: Dion Georgopoulos

Cinemas are also doing a roaring trade, though a power outage unrelated to the weather has affected Hoyts Broadway in Ultimo, causing screenings to be cancelled.

Shoppers at the Queen Victoria buildingCredit: Dion Georgopoulos

NSW Ambulance has seen a 20 per cent increase in calls today, as Sydney and its surrounds endure extreme heat.

Ambulance Chief Superintendent Mark Gibbs said paramedics expected to receive an extra 500 calls by midnight, compared to a typical summer Saturday.

“At the moment, we are meeting that demand. But we will continue to monitor that throughout the evening,” he said.

Paramedics are expected to respond to an extra 500 calls for help today, 20 per cent more than a normal summer day.Credit: Louise Kennerley / SMH

Gibbs urged people in Sydney, particularly those attending music festivals this afternoon, to stay hydrated and be aware of signs of dehydration and health impacts from the heat, including lethargy, feeling fatigued, vomiting, muscle twitching and in extreme cases, fitting.

“In those cases, if you are concerned, ring Triple Zero,” he said, asking people to also check on elderly neighbours and others who may be impacted by the heat.

Sydney’s beaches, rivers and pools are delivering welcome relief from the extreme heat today for people but where can you take your dog for a swim?

 Scottie walks his cattle dog through the water to cool him down in the Nepean River at Yarramundi where people are seeking refuge from stifling heat. At 1pm the temperature at Yarramundi hit 42 degrees and expected to hit the mid-forties later.Credit: Dean Sewell

It’s not just people who need to cool down, pets are also sweltering and may need some help to stay hydrated and healthy. While most beaches in Sydney don’t allow dogs, there are a few options listed below. Check with your local council for more options.

Northern Beaches: Clontarf, Flora and Ritchie Roberts Reserve, Curl Curl Rowland Reserve, Bayview, Manly Lagoon, Manly Eastern suburbs: Kutti Beach, Vaucluse, MacKenzies beach, Rose Bay Foreshore, Dumaresq ReserveSouthern suburbs: Greenhills Beach, Cronulla, Silver Beach, Kurnell Lady Robinsons Beach, Kyeemagh, Horderns Beach, Bundeena

North shore: Mosman - Clifton Gardens Reserve, and Sirius Cove

Ethan and Isabel arrive with their eski for the day at the Nepean River in Yarramundi. Credit: Dean Sewell