A Bureau of Meteorology spokesperson told ABC News this morning that "a weak change should drop temperatures a little bit this evening, but it's quite a short lived change and it will get warm again tomorrow ... it shouldn't get as hot, but western parts of Sydney should see 40C tomorrow again," the spokesperson said.
Sydney's temperature record was almost broken this afternoon - when the mercury hit 47.3 degrees in Penrith, at 3.25pm today.
That's the second hottest day in Sydney's 158 years of recorded history.
#SydneyHeat: Sorry, in our earlier checks we missed a 47.8 degrees C temperature recorded at an old #Richmond station (now closed) in 1939. 47.3 today still beats the previous #Penrith record.
— Bureau of Meteorology, New South Wales (@BOM_NSW) January 7, 2018
Today's scorching temperature beats the previous record for the area, and came only 0.5 degrees off claiming the record - set in 1939.
The Bureau of Meteorology mistakenly tweeted that today's temperature was the all-time record, before discovering the historical date.
#SydneyHeat According to preliminary data #Penrith has broken the all time maximum temperature record for both this station and the Sydney Metropolitan area with 47.1 degrees at 1:55pm. Previous record 47.0 on 11/2/2017. Latest observations: https://t.co/GORSOnwOjj.
— Bureau of Meteorology, New South Wales (@BOM_NSW) January 7, 2018
There's a total fire ban in place for the Greater Sydney and Hunter regions, as much of Australia's east struggles through the record heatwave.
Authorities say the hot conditions are not expected to ease until Tuesday.
The NSW Office of Environment and Heritage also warned of higher than normal ozone levels, issuing an Air Quality Forecast alert of poor.
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