Perth has a Mediterranean climate with hot, dry summers and mild, wet winters. Average highs reach 30°C in February and drop to around 17°C in July, while annual rainfall totals about 719 mm, with the vast majority falling between May and September.
A Mediterranean Climate With Distinct Seasons
Perth sits on the southwest coast of Western Australia and falls into the “distinctly dry summer” temperate category under the Köppen climate classification used by the Bureau of Meteorology. In practical terms, this means two very different halves of the year: a long stretch of warm, sunny, and almost rainless weather from October through April, followed by a cooler, greener period from May to September when most of the rain arrives. If you’ve experienced the climate around the Mediterranean Sea, coastal California, or parts of Chile, Perth will feel familiar.
Summer Temperatures: December to February
Perth’s summers are genuinely hot. Average daily highs sit at 27.4°C in December, climb to 29.7°C in January, and peak at 30.0°C in February. Overnight lows hover between 16°C and 18°C, so evenings cool down enough to sleep comfortably. Heatwaves are common, though, and stretches above 35°C happen multiple times each summer. Humidity stays low during the hottest months, which makes the heat more bearable than in tropical Australian cities like Darwin or Cairns.
One of the most talked-about features of Perth summers is the Fremantle Doctor. This is a reliable afternoon sea breeze that sweeps in from the southwest, typically arriving in the late afternoon and dropping temperatures noticeably within an hour. Locals treat it almost like a weather event. Once the Doctor arrives, the heat of the day is essentially over.
Winter Temperatures: June to August
Winters are mild by global standards. July is the coldest month, with an average high of 17.4°C and an average low of 9.0°C. Frost is rare in the city itself, though inland suburbs closer to the Darling Scarp occasionally dip near freezing on clear nights. June and August are similar, with highs around 18°C. You’ll need a jacket, but Perth never sees snow. The transition months of May and September feel like spring or autumn in many Northern Hemisphere cities, with comfortable highs around 20°C.
Monthly Temperature Overview
Here’s how temperatures move through the year, based on long-term Bureau of Meteorology records for Perth:
- January: highs 29.7°C, lows 17.9°C
- February: highs 30.0°C, lows 18.1°C
- March: highs 28.0°C, lows 16.8°C
- April: highs 24.6°C, lows 14.3°C
- May: highs 20.9°C, lows 11.7°C
- June: highs 18.3°C, lows 10.1°C
- July: highs 17.4°C, lows 9.0°C
- August: highs 18.0°C, lows 9.2°C
- September: highs 19.5°C, lows 10.3°C
- October: highs 21.4°C, lows 11.7°C
- November: highs 24.6°C, lows 14.0°C
- December: highs 27.4°C, lows 16.3°C
Rainfall: Almost All in Winter
Perth receives about 719 mm of rain per year, but the distribution is extremely lopsided. July alone accounts for 147 mm, and June adds another 127 mm. The three wettest months (June, July, August) deliver more than half the annual total. Winter rain typically comes in frontal systems sweeping in from the Indian Ocean, bringing grey skies and steady showers that can last a day or two before clearing.
Summer, by contrast, is almost bone dry. December averages just 9.6 mm of rain, and January and February are barely wetter at 15.9 mm and 12.7 mm respectively. It’s common to go weeks in summer without seeing a single drop. This dry stretch is why Perth’s parks and lawns turn brown by late January unless they’re irrigated, and it’s a major factor in the region’s bushfire risk during the hotter months.
Sunshine and UV Exposure
Perth averages about 8 hours of sunshine per day across the full year, making it one of the sunniest cities in Australia. January is the standout month, logging roughly 387 hours of sunlight. Even in winter, clear days are frequent between rain systems, giving Perth a brighter feel than cities at similar latitudes in the Northern Hemisphere.
That sunshine comes with serious UV intensity. In January, Perth’s average daily maximum UV index hits 12, which is classified as “extreme.” It stays at 10 or above from November through February. Even in September and October, the UV index reaches 6 to 8, high enough to cause sunburn in under 30 minutes for fair skin. The UV index only drops to moderate levels (3 to 4) during June, July, and August. Sun protection is relevant for most of the year here, not just in summer.
A Drying Trend Over Recent Decades
Perth’s climate has been getting noticeably drier. Since the mid-1970s, winter rainfall across southwest Western Australia has declined by about 16%. That may sound modest, but the impact on water supply has been dramatic: streamflow into Perth’s major reservoirs has dropped by more than 50% over the same period. The city has adapted by building desalination plants and tapping groundwater, but the shift is real and ongoing. Climate models project a further median decline of around 8% in rainfall under future warming scenarios, meaning the trend is likely to continue rather than reverse.
What Perth’s Climate Feels Like Day to Day
If you’re planning a visit or a move, here’s the practical picture. Summer days are hot and bright with low humidity, cooling off reliably each evening once the sea breeze kicks in. You’ll want sun protection any time you’re outdoors, and air conditioning is standard in homes and businesses. Winter brings stretches of rain interspersed with crisp, sunny days. It rarely feels bitterly cold, but a warm layer and a waterproof jacket are essential from June through August. Spring (September and October) and autumn (March and April) are widely considered the most pleasant seasons, with mild temperatures, manageable UV levels, and relatively little rain.
Compared to Australia’s east coast capitals, Perth is drier, sunnier, and has a more predictable seasonal rhythm. Sydney and Melbourne both receive rain year-round, while Perth’s wet season is concentrated and its dry season is genuinely dry. That predictability is one reason outdoor life, from beaches to barbecues, is so central to Perth’s culture.