September this year was the warmest on record in the entire western Australia, with daytime high temperatures approximately 2.18 degrees Celsius (3.92 degrees Fahrenheit) above average.
For Perth, the average maximum for the month was 22.9C (73F), which is 2.6C (4.7F) higher than the usual September average of 20.3C (68.5F).
"This was helped along by a good nine days above 25 degrees [C] during September, including two days over 30 degrees [C]," said forecaster Angus Moore of Australia's Bureau of Meteorology (BOM).
The high temperatures were accompanied by a significant lack of monthly rain. The 31.4 millimetres (1.23 inches) recorded in Perth's official Mount Lawley gauge fell short of its 84.8mm September average.
"That makes it the driest September we've seen since 1977," Moore said.
The weather in the southwest was dominated by high pressure, keeping rain-bearing cold fronts away from land.
"As a month in the transition season between winter and summer, we still expect to see pretty vigorous cold fronts coming through during September," Moore said.
"This time around we just haven't seen those fronts moving through the southwest corner of the state as often as we might expect."
Rainfall is expected to be below average across most of Australia for the rest of the year and early 2020.
The exception is western Australia's northwest, where there are slightly increased chances of above-average rainfall between October and December.
Elsewhere in Australia, September was a month of wide-ranging weather fluctuations.
Bushfires raged in parts of Queensland and New South Wales, strong winds whipped up dust storms and snow fell at low elevations.
There was widespread frost across inland areas during the middle of September and heavy rain on the east coast, with Sydney receiving nearly a month's worth of rain in one day.
The BOM Climate Outlook suggests maximum temperatures are likely to be above average across much of Australia during the remainder of the year, increasing the chance of early heatwaves.
With less cloud about, nights are likely to be cooler than average across parts of southeastern and northern Australia between October and December, with warmer nights likely elsewhere.