Temperatures in Perth will be heading for a record November high of 40 degrees tomorrow.
According to the bureau of meteorology Perth, it will be the earliest in November that Perth has experience a 40C day and only the fourth 40C day in November in the city since the 19th Century.
People planning on hitting the outdoors in Perth on Saturday have been warned to protect themselves from an extreme UV Index, which is tipped to reach 11 between 8am and 3.50pm.
However, the heatwave will be short lived as the temperature is expected to dip by 13 degrees on Sunday.
The cool change in the weather will see temperatures dropping to the mid 20s in west coastal parts and extend across the whole of southern WA by Monday and according to Neil Bennet of the bureau of metrology is completely normal.