Australia’s climate ranges from tropical in the far north to temperate in the southeast, with a vast arid interior covering most of the continent. The country spans six major climate zones and has no cold or polar regions. Seasons are reversed from the Northern Hemisphere: summer runs from December to February, and winter from June to August.
Six Climate Zones Across One Continent
Australia’s Bureau of Meteorology divides the country into six major climate classes based on the types of vegetation each region can support: equatorial, tropical, subtropical, desert, grassland, and temperate. Within those six classes sit 28 sub-classes, which gives a sense of how much variation exists across a single landmass roughly the size of the contiguous United States.
The arid zone dominates. About 70% of the continent receives less than 500 mm of rain per year, and the driest interior regions get under 250 mm. This enormous dry center, often called the Outback, is flanked by a green, wetter fringe along the coasts and the tropical north. If you picture a giant donut of habitable land around a hot, dry middle, you have a rough mental map of Australian climate.
The Tropical North: Wet Season and Dry Season
Northern Australia doesn’t follow the four-season calendar the rest of the country uses. Instead, it has two distinct periods: a wet season from October to April and a dry season from May to September. The dry season brings abundant sunshine with daytime highs in the low 30s °C (upper 80s °F) and comfortable overnight lows. It’s the time of year most people choose to visit places like Darwin, Cairns, and the Kimberley.
The wet season is a different experience entirely. Temperatures rarely drop below 21 °C (70 °F) even at night, coastal areas stay above 24 °C, and humidity sits above 60% for months on end. Most of the region’s annual rainfall arrives in intense bursts during this period, often accompanied by thunderstorms, cyclones, and localized flooding. Darwin, for example, records UV index values of 12 or 13 in nearly every month of the year, making sun protection a year-round concern in the tropics.
The Arid Interior
Central Australia is defined by extremes. The continent’s all-time highest temperature, 50.7 °C (123.3 °F), was recorded at Oodnadatta in South Australia on January 2, 1960. Summer days in the desert interior regularly exceed 40 °C, but because dry air loses heat quickly after sunset, overnight temperatures can plunge by 20 °C or more. Winter nights in the desert frequently drop below freezing, even though daytime temperatures may still be pleasant.
Rainfall in the interior is sparse and unreliable. Some years a region will receive almost nothing; other years, a single weather event can deliver most of the annual total in a few days, briefly transforming dry creek beds into rivers and barren plains into fields of wildflowers.
How Major Cities Compare
Most Australians live along the coast, where climates vary significantly from city to city.
Brisbane is the most subtropical of the major cities. It averages around 19 muggy days per month in January, and humidity stays noticeable from November through March. Winter is mild and dry, with clear skies more than 80% of the time from July through September.
Sydney sits in a transitional zone between subtropical and temperate. Summers are warm and moderately humid, with roughly 10 to 11 muggy days per month in January and February. Winters are cool but not cold, and the city enjoys its clearest skies in late winter and early spring.
Melbourne is famously unpredictable. It has the lowest chance of clear skies among the five largest cities, hovering around 55 to 60% through the cooler months. Humidity is rarely oppressive, with only about one muggy day per month even at the peak of summer. The city can experience four seasons in a single day, swinging from warm northerly winds to cool southerly changes within hours.
Perth has the most consistently sunny climate of any major Australian city, with clear skies 70% of the time or more in every month of the year and peaking above 85% in January. Summers are hot and dry, winters mild and wet, following a classic Mediterranean pattern. Muggy conditions are rare, topping out at about two days per month in February.
Adelaide is the driest of the state capitals and has almost no muggy days at all. Its climate resembles Perth’s Mediterranean pattern but with slightly less sunshine and hotter summer extremes, since it sits closer to the arid interior.
What Drives Australia’s Rainfall Patterns
The single biggest influence on year-to-year rainfall variation in Australia is the El Niño-Southern Oscillation, a cycle of warming and cooling in the Pacific Ocean. El Niño phases tend to bring drier conditions, while La Niña phases bring wetter ones, but the two are not mirror images of each other.
La Niña acts as a widespread, long-lasting intensifier of rainfall across eastern and northern Australia throughout its entire lifecycle. It increases both average rainfall and the likelihood of extreme wet months. El Niño’s drying effect, by contrast, is more limited. It mainly suppresses rainfall during winter and spring in the southeast and northeast, and its impact typically lasts only three to four months in any given location. Research published in Geophysical Research Letters found that El Niño can actually increase rainfall during its mature phase in some areas during the December-to-February window, a counterintuitive result that complicates simple “El Niño equals drought” assumptions.
This asymmetry matters. A La Niña event can reliably signal months of above-average rain across a wide area, while El Niño’s effects are patchier and shorter-lived. Southern Australia has also seen a broader shift toward drier conditions since the 1950s, with more frequent years of below-average rainfall independent of any single El Niño event.
UV Exposure Across Latitudes
Australia has some of the highest ultraviolet radiation levels on Earth, driven by its latitude, clear skies, and relatively thin ozone layer during the Southern Hemisphere summer. Peak daily UV index values regularly hit 12 to 14 across much of the country in summer and can reach 16 to 17 in the far north.
The difference between northern and southern cities is striking. Darwin’s UV index stays at 8 or above in every single month, meaning sun protection is necessary year-round. Melbourne, at the opposite end, drops to a UV index of just 2 in June and July, roughly comparable to a mild spring day in Northern Europe. Sydney and Brisbane sit in between, with UV levels high enough to cause skin damage from September through April. Hobart, the southernmost capital, has the lowest UV exposure, peaking at 8 in January and dropping to 1 in winter.
Temperature Records and Warming Trends
Australia’s temperature range spans more than 73 degrees Celsius. The hottest reading on record is 50.7 °C at Oodnadatta, and the coldest is −23.0 °C at Charlotte Pass in the Snowy Mountains of New South Wales, recorded on June 29, 1994. That low came from a high-altitude weather station at about 1,760 meters, one of the few places in Australia that regularly sees snow.
The continent as a whole is getting warmer. Australia’s average temperature has risen by 1.51 °C since national records began in 1910, according to the Bureau of Meteorology’s 2024 State of the Climate report. That warming has brought an increase in extreme fire weather and a longer fire season across large parts of the country since the 1950s, particularly in the south and southeast where drying trends compound the effect of higher temperatures.