Penrith is set to produce some ironic weather history this weekend with the city likely to record its coldest ever temperature, just six months after its hottest day on record.
The mercury rocketed to 46.9 degrees on February 11 this year, breaking new ground.
But that will be a distant memory if Penrith records a temperature of -4 tomorrow morning, as is being predicted by Weatherzone.
The current lowest temperature on record is -1.4 degrees, set in July 2002.
Penrith has never produced its hottest and coldest day on record in the same year before.
The Bureau of Meteorology says there will be patchy fog in Penrith in the morning, as well as plenty of frost. The temperature will eventually reach 19 degrees.
The freezing weather is likely to cause havoc with early morning junior sporting fixtures.
Not even Katoomba in the Blue Mountains is predicted to be as cold as Penrith this morning, with the Bureau predicting temperatures to drop to -3 degrees, far from the -8.2 degrees record set in 1977.