As seasons of the year in Australia begin to change in character there is some value in establishing what the climate zones across the country's 7.688 million km² landmass are, in order to form personal comparisons that are based on more than childhood memories when attempting to confirm our sense of what Spring, Summer, Autumn and Winter is in 2024.
According to the Australian Bureau of Meteorology (BOM); "Australia is one of only a few countries in the world to span several climate zones".
There is a tropical zone in the north, a subtropical zone across much of our centre and, temperate zones in the south.
This simplified outline of the spatial distribution of these zones is based on meteorological opinion in 2018.
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Again according to BOM these are the principal characteristics of these zones:
Tropical zone
Areas near the equator get direct sunlight all year round, meaning that at noon the sun is right overhead. This is called the tropical zone.
When the sunlight hits the surface of the earth or the ocean it warms the air, causing it to rise. The warm air cools as it rises, and the water in the air condenses and falls as rain.
It makes sense then that the tropical zone, which includes places like Cairns and Darwin, is warm and humid most of the year, with a clear wet and dry season as the tropical rain belt shifts south and then north of the equator.
Subtropical zone
If you move further away from the equator, you enter the subtropical zone. This is where the warm rising air air from the tropics falls as dry, cooler air. The sinking air makes for high pressure systems and clear skies at the Earth's surface, so the subtropical zone is fairly dry.
Places like Longreach and Brisbane are considered subtropical. Summers are hot, winters are mild and this zone is where you’ll find most of the world's deserts.
Temperate zone
The next climate zone is the temperate zone. The Earth is round, so sunlight hits these areas on more of an angle then at the equator. The same amount of energy then has to cover a larger area so it’s cooler here than in the tropics.
The Earth is also tilted, so as we move around the sun during the year, temperate zones receive less direct sunlight in winter and more in summer.
Places in the temperate zone—like Hobart and Melbourne—therefore have distinct seasons, with warm, long days in summer, and cold, short days in winter. Most regions in the temperate zone also tend to receive more rainfall in winter than in summer.
Polar zone
The coldest climate zone is the polar zone. Here, the sun is lower in the sky and its rays reach Earth at an even larger angle.
The polar zone is very cold and cold air can't hold much moisture. Some areas in the Arctic and Antarctica are as dry as the subtropical deserts!
So does the climate in the region where you live still feel like the regional climate as you remember it from ten, fifteen, twenty or forty years ago?
Given that by 2023 Australia had a national average surface temp of 1.50°C ± 0.23°C above pre-industrial levels, which has led to an increase in the frequency of extreme heat events.
That in recent decades, there has also been a trend towards a greater proportion of rainfall from high intensity, short duration rainfall events, especially across northern Australia during the wet season.
As for April to October rainfall, it has declined across southern Australia in recent decades, due to a combination of long-term natural variability and changes in atmospheric circulation caused by an increase in greenhouse gas concentrations.
Does it still seem like climate as usual, given in 2023 this country experienced its equal eighth-warmest year on record with the national mean temperature 0.98 °C warmer than the 1961–1990 average. With mean annual maximum and minimum temperatures were above average for all six states and the Northern Territory. While Winter in 2023 was Australia's warmest on record, with the national mean temperature 1.53 °C above the 1961–1990 average and Summer was peppered by frequent low-to-severe intensity heatwave conditions.
It was a year in which during the first quarter, Australia experienced multiple major flood events, mostly across inland and northern regions and then come the August to October period the country experienced its driest three month period on record since 1900.
Surface water storages declined but bounced back to 74% of available national capacity by year's end.
Come 2024 and it seemed that Australia's climate and weather patterns lurched between extremes with Nature trying to find some sort of balance despite the fact that the national land surface temperature still remains at 1.50°C ± 0.23°C above pre-industrial levels with a reasonable chance that it will end the year even higher.
BOM's Seasonal Summary for Australia in Autumn 2024 revealed that a heatwave affected most of south-eastern Australia in the first half of March, with both daytime and night-time temperatures more than 10 °C above the March average, while parts of Western Australia's far west experienced very much above average temperatures in all three autumn months. In May, Perth Metro had 13 consecutive days of at least 25.0 °C, a May record for the combined sites of Perth.
The Summary also stated that the national area-averaged mean temperature for autumn was 0.53 °C above the 1961–1990 average and 0.46 °C above the 1961–1990 autumn area-average mean maximum temperature.
Adding that Area-averaged maximum temperatures were above average for all states, while for the Northern Territory it was 0.88 °C below average and the lowest since 2012.
Mean maximum temperatures were above average to very much above average (in the highest 10% of all autumns since 1910) for Victoria, Tasmania, most of New South Wales and South Australia, a large area in the western part of Western Australia, the Top End of the Northern Territory and coastal and inland areas of central Queensland. Autumn maximum temperatures were the highest on record for parts of Western Australia's west coast, with many stations in these areas having their highest mean maximum temperatures records for autumn.
Mean maximum temperatures were below average to very much below average (in the lowest 10% of all autumns since 1910) for inland areas of the Northern Territory and Western Australia.
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