Snow in Western Australia:
Mountain snowfalls are typically confined to the higher peaks of the Stirling Range in the state’s south. Situated about 90km inland from Albany, this is a range of rugged peaks rising abruptly from low-lying and mostly flat farmland. Five of the peaks rise to over 1000m, with the highest being Bluff Knoll at 1095m. Although not a great height as far as mountains go, in this region it is high enough to receive occasional light snowfalls in most years.
The southwest corner of Western Australia
Sometimes, but far less often, snow may also fall on the Porongorup Range. This is a smaller, lower range (highest point 670m) between the Stirling Range and the coast. However, if snow falls on the Porongorups it will have also fallen in greater quantity on the Stirlings, and so Bluff Knoll is the focus for snow-seekers in WA.
Outside of the Stirling and Porongorup Ranges, the only other significant mountains in WA are too far north and of insufficient height to attract snow. Some areas in the southwest which have received rare snowfalls are hilly (eg Perth Hills and around Greenbushes), but these are generally considered as low level falls.
When It Falls
The earliest that snow has been recorded in WA is April 20th (1970), and the latest is November 19th (1992), however it is very improbable towards the ends of this range. Since WA was settled by Europeans (Albany in 1826, Perth in 1829) only three falls have ever been reported in November, and only four falls prior to June.
As the monthly distribution chart shows, the best likelihood of finding snow is in the July to September period. July and August are the coldest months of winter, and although September marks the start of spring, good wintry outbreaks can still occur and the mountain has cooled further. One of the heaviest falls in recent decades occurred in early October, so early spring should not be discounted.
When snow does fall, the best accumulation occurs overnight or in the morning when temperatures are lower. Snow showers may occur at any time of day, but even on the coldest days on the highest peaks maximum temperatures are above freezing, even if only just, and melting occurs.
How Often It Falls
Since 1965, reports of snowfalls known to the Bureau of Meteorology (as listed in the historical data page) suggest an average of just over one snow event per year, as shown on the chart below. Prior to this, reports become progressively less complete the further back in time one looks. Low level falls are much less frequent than those on the Stirling / Porongorup peaks, and appear to be decreasing with time. Whether this reflects climate change or not is hard to say, because of the probable incompleteness of the snow records.
Total number of known snow events in WA each year, from 1965 to 2003.
Each horizontal line indicates one day on which snow was reported in WA;
white asterisks (*) indicate snow at low levels as well as on the peaks.
It is not known with certainty how often it snows on the Stirling Ranges. Anecdotal evidence suggests snow may settle on Bluff Knoll two or three times per year on average, with the possibility of a couple more very light falls going unwitnessed or unreported. Instances of snowflakes briefly falling but not settling on the ground - such as in precipitation downdrafts over ground that isn’t cold enough - may occur more often.
The uncertainty is due to the lack of people in a position to clearly see the snow on the mountains. The Stirling Range sits in a large national park surrounded by thinly populated farmland; apart from the nearby ranger’s residence and caravan park (altitude only 218m, below the snowflakes), there simply aren’t many observers around. Light snow on the summits can be hard to spot from below and at a distance, even if not obscured by cloud, and when clear, a light dusting melts quickly. Falling snowflakes might only be seen by people climbing the summits, but few people do this in the inclement weather required for snow, especially outside of weekends and school holidays.
The photo above right is an example of a light snow cover, with ice coating the bushes, that would be hard to discern by a distant observer looking upwards.
How Much Falls
Generally less than five centimetres accumulates on the Stirling Range summits, with only the upper portions of the mountains being affected.
The biggest fall in recent times was in 1992 (October 6) when 20cm was recorded on Bluff Knoll, with snow on the ground all the way down to the car park (altitude approx 450m). Another fall of 20cm was reported in 1998 (July 26), and two falls of 10cm occurred in 1986 (July 15 and August 12). These four occasions were the only falls in the last twenty years to have exceeded 5cm. Prior to that, depth measurements are scarce, but falls described as "heavy" are equally uncommon. On the Stirling Ranges, anything more than a couple of centimetres is cause for celebration.
The Stirling Ranges are very rocky and thickly vegetated, so, other than photography, snowman building and snowball fights are the only snow activities that can be accommodated. Unfortunately skiing, snowboarding or tobogganing are not practical given the terrain and lack of snow depth. An unprecedented low-level snowfall covering the access roads would be needed for this.
The photo above shows that even with up to 5cm of snow, the thickly vegetated peaks only look slightly whitened from a distance. It takes 10 to 20cm of snow to make the peaks appear distinctly snow-capped from afar.
How Long It Lasts
Thanks to the marginal conditions and small quantity, West Australian snow doesn’t persist for long. A typical light fall on the Stirling Range summits melts or is washed away within a day of it falling. The longest lasting known snowfall in WA occurred in 1923 when snow remained on the Stirlings for four days, and heavy falls in 1992 and 1998 lasted about two days, but these were rare exceptions. Even during WA’s most widespread snow event in 1956 (June 26), the Stirlings’ snow had all melted by the following morning.