If it feels like Australian summers are getting longer and hotter, that is probably because they are. The summers many Australians grew up with no longer exist.

Climate change has already altered the Australian seasonal calendar. Since the middle of last century, summers have expanded and become more extreme, while other seasons have contracted. These trends will continue unless emissions are reduced and until emissions reach net zero.

This report examines changing seasons using data from the Bureau of Meteorology (BOM). Temperatures that once marked the start and end of summer are shown to occur much earlier and later.

Data is drawn from 70 weather stations across southern Queensland and WA, NSW, Victoria, ACT, South Australia and Tasmania. These subtropical and temperate areas are were most Australians live.

Key points:

In the two decades 1999-2018, compared to the mid-twentieth century benchmark:

• Summer temperatures were experienced for a full 31 days longer than the benchmark, and
• Winter temperatures were experienced for 23 days (over three weeks) less than the benchmark.

In most recent years (2014-18) the trend has continued, leading to Australians experiencing summers that were twice as long as winters.

All Australian capital cities experienced longer summers and shorter winters

Some regional areas of Australia such as Port Macquarie NSW, are experiencing even more dramatic changes to the length of seasons, and are now seeing seven more weeks of traditional Summer temperatures compared to the 1950s and 60s.