A statewide air quality warning has been issued for Victoria after smoke haze from the NSW bushfires combined with dust from the state’s far north-west and grey out much of Melbourne.

A Bureau of Meteorology spokesman said the smoke had travelled overnight from the massive blazes in southern and eastern NSW, while the dust had been blown across the whole state.

Melbourne was shrouded in a grey haze by mid-morning on Friday, as it heated up to a predicted scorching 43 degrees.

Metropolitan Fire Brigade crews answered calls to several buildings across the city as thick smoke triggered fire alarms.

High-rise office workers posted “yesterday and today” photographs of Melbourne’s skyline, as the EPA described air quality at 2pm as “moderate”. By 3pm, as the dust moved in, that had become “very poor” and “hazardous”.

#AirQuality update: Forecast is VERY POOR to HAZARDOUS in east Gippsland and in parts of north east Vic. Impacts of VERY POOR to HAZARDOUS are likely in northern Vic and further south into Melbourne. Visit AirWatch for the latest updates https://t.co/JgoucU885D pic.twitter.com/KGbn6CdCdt

— Environment Protection Authority Victoria (@VicGovEPA) December 20, 2019

This is quite incredible; the State Control Centre says the smoke haze that has shrouded #Melbourne is from the NSW bushfires @9NewsMelb @9NewsAUS @vicemergency #melbourneweather #NSWbushfires #NSWfires pic.twitter.com/rsYbCgUOpN

— Tom Kelly (@tpwkelly) December 20, 2019

This is completely normal.. #NSWfires #melbourneweather pic.twitter.com/xfhiSLi9ta

— Veryan Croggon (@veryanc) December 20, 2019

Four fires burning in Gippsland, in eastern Victoria, were also to blame for the smoke. Vision was reduced to about a kilometre in some places, the bureau said.

Vic Emergency issued an air quality warning at 1pm (AEDT), saying light winds meant smoke would continue to affect air quality until Saturday morning.

“You will see or smell smoke across parts of the state of Victoria. Smoke in the Hume region is as a result of fires in NSW. Smoke in Gippsland region is as a result of fires currently burning in Gippsland,” it said.

“Light winds are likely to mean that smoke continues to impact air quality until Saturday morning.”

There is a fire ban for the entire state of Victoria on Friday, with “very high” to “extreme” fire danger ratings across the state. It came as the state recorded its hottest December day on record, with Hopetoun, in the north-west, cracking 47.4 in the afternoon.

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A statewide smoke warning (air quality) has been issued for Victoria. This video shows the smoke from NSW fires coming down across the state. There is also smoke around from the fires in East Gippsland. Video: BOM

For more information on this warning, see https://t.co/Hvsl7hmdkY pic.twitter.com/Ys8saukYsC

— cfa_updates (@CFA_Updates) December 20, 2019

Our webcam at Kilmore captured the tide of smoke as it moved over the ranges before reaching #Melbourne. The smoke is trapped under an inversion but is expected to gradually disperse as temperatures increase and ventilation improves. Check @EPA_Victoria for air quality info pic.twitter.com/GgEEnVcAz1

— Bureau of Meteorology, Victoria (@BOM_Vic) December 20, 2019

Victorians were also urged to take as much pressure off the electricity grid as possible as the deadly heatwave hit.

“The experts assure us that we have sufficient energy supply for today,” Health Minister Jenny Mikakos said.

“But it is sensible to not turn on your dishwasher and your washing machine and all your electrical appliances on days like today.”

There won’t be any reprieve from the heat until early evening, before cool air at midnight.

“The cool change is still on track and is still later than anyone would want,” Bureau of Meteorology senior meteorologist Keris Arndt said.

“We will slowly cool down with the sun going down but we won’t have any cool air until about midnight.”

What my office view normally looks like, compared to today, where smoke from the NSW bushfires has drifted across Melbourne. Can’t imagine what the poor folk closer to the fires are living through. It’s frightening. pic.twitter.com/QR1qntRUoA

— Kate McMahon (@katejmcmahon) December 20, 2019

Victoria’s Country Fire Authority said nearly 500 firefighters were battling three uncontained fires in East Gippsland.

There were also more than 260 firefighters still at the contained Tambo Crossing fire.

A further 118 firefighters were patrolling blazes at Somerton, on Melbourne’s northern oustskirts.

-with AAP