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Live forecasts update automatically; written guidance last reviewed 23 June 2026 by the Reef Brief Weather Desk. Data from the Bureau of Meteorology (BOM) and other national met services via Open-Meteo.
A polar air mass over Western Australia brings a sharp drop in temperature, gusty southerly winds, and widespread frost inland. Conditions will feel much colder than the live forecast above suggests, especially at dawn and during the afternoon.
What is a polar air mass?
A polar air mass originates over the Southern Ocean near Antarctica. It is cold, dry, and stable, and it pushes north across Western Australia behind a strong cold front. Unlike a normal winter pattern, this air mass produces a prolonged period of cold weather rather than a brief shower event.
How long will the cold last?
The polar air mass lingers for 3 to 5 days as it slowly moves east. Overnight lows in the agricultural and southern districts can fall below 0 °C. Daytime maxima stay 5–8 °C below the seasonal average. The most intense cold usually occurs on the second and third mornings with clear skies and light wind.
Is a polar air mass unusual for WA in winter?
It occurs several times each winter. The main difference is the depth of cold air, which can bring sub‑zero minima as far north as the Mid West. It is not exceptional but always needs preparation for frost and wind chill.
Will there be rain or snow?
Rain is unlikely because polar air is very dry. The exception is a light drizzle on the south coast during the first 24 hours. Snow is extremely rare in WA and does not occur with this type of air mass.
What should I do to protect plants and pipes?
Cover sensitive plants with frost cloth or hessian. Drain exposed irrigation pipes and tap off outdoor taps. Bring pets inside overnight. Check the severe weather warning page for frost alerts issued by the Bureau.
For more details on cold outbreaks across Australia, see the Australia weather hub. If you’re travelling east, the polar air mass often reaches South Australia within 48 hours, so check local forecasts.