Sydneysiders responded to the near-record heat with the highest water use in 15 years, with another bout of heat likely to build by the end of the week.
Unstable conditions after another scorcher on Monday prompted the Bureau of Meteorology to issue a severe thunderstorm warning for Sydney and a strip of along most of inland coastal NSW from near Taree down to the Victorian border.
The city's top on Monday of 31.9 degrees was again eclipsed by severe heat in the western suburbs, with 43.6 degrees in Richmond.
Penrith backed up Sunday's 47.3 degrees - the hottest in the Sydney Basin in 79 years and the warmest for the day on Earth - with 42.5 degrees on Monday.
The bureau said severe thunderstorms were likely to produce damaging winds in the warning area (see below) over the next several hours.
Locations which may be affected include Newcastle, Gosford, Sydney, Wollongong, Batemans Bay, Orange, Canberra, Wagga Wagga, Albury, Tibooburra, Cobar, Bourke and Broken Hill, it said.
Tuesday won't bring much relief until the late afternoon or evening, when winds shift around to the south. Before then, however, the mercury is again expected to climb to 31 degrees in the city and 37 across western suburbs, the Bureau of Meteorology said.
A thunderstorm is likely, "possibly severe", the bureau said.
A couple of days of more average temperatures should then make way for another burst of heat by Friday and Saturday, Craig McIntosh, a meteorologist with Weatherzone, said.
Western suburbs, in particular, "could start reaching the high 30s again", Mr McIntosh said, adding that sea breezes should again spare the coast from the worst of the heat.
While models are yet to settle, another spell of warm days should arrive by the middle of next week onwards. "We're not going to escape the heat at the back of the month," Mr McIntosh said.
Surge in water use
The weekend heat had many people dousing themselves and their gardens to keep cool, if the latest Sydney Water figures are anything to go by.
Sunday's water demand over Sydney Water's area of operations reached 2.27 billion litres, according to Robert Ius, hydraulic operations manager at the agency.
That tally exceeded the 2017 peak demand day of 2.215 billion litres on February 5, and was the most since January 29, 2003, when use reached 2.273.
Sunday's demand was 762 million litres - or about 50 per cent - above the long-term average daily water use in January, Mr Ius said.
So far this summer, average daily water demand is running 5 per cent above the level of a year earlier. The 2016-17 summer was Sydney's hottest on record, according to the Bureau of Meteorology.
Sydney's water storages remain at 81 per cent capacity, according to WaterNSW.
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