Despite the rain, we’ve just had the third hottest summer on record

What do you get when you cross the El Nino climate system with an ocean heatwave? Australia’s hot, wet summer.

The average, minimum and maximum temperatures for December, January and February added up to the third hottest summer on record, reported in Friday’s quarterly release from the Bureau of Meteorology.

BoM climatologist Caitlin Minney said the hottest summer on record was 2018, followed by 2019, and records were tumbling at a more regional level. “There is an increase in the recency of those records because of climate change,” she said.

Rainy and stormy weather in Sydney in January.Credit: Dion Georgopoulos

In NSW, it was the 10th hottest summer on record, and in Queensland it was the sixth hottest. Thursday was the hottest February day for Sydney since 2020 and Brisbane set a record at 61 nights above 20 degrees.

The report comes as global data from ERA5 showed January was the warmest January on record for both surface air and sea temperatures, after 2023 shattered the 2016 record for the hottest year. The global average temperature of 14.98 degrees in 2023 was close to 1.5 degrees above pre-industrial levels.

The hottest day of the Australian summer was 49.9 degrees at Carnarvon Airport in Western Australian on February 18 and the warmest night was 36.4 degrees at Birdsville Airport in Queensland on January 26.

A swimmer cools off on a sultry summer’s day.Credit: Dallas Kilponen

The season was also abnormally wet, as rainfall was 19 per cent above the 1961-1990 average for summer. In NSW, it was 16 per cent higher, in Queensland it was 30 per cent higher, and in Victoria it was 56 per cent higher, while Tasmania and Western Australia had lower rainfall than average.

While it was an El Nino summer, Minney said higher ocean temperatures tended to bring more rainfall, and could also increase humidity. Often the heat and rainfall could coincide with an afternoon thunderstorm following a hot, humid day.

El Nino increases the probability of hotter, drier weather, while the other side of the same climate system, La Nina, more commonly brings rain. However, the effect of El Nino is strongest in winter and spring rather than in summer, and it is stronger west of the Great Dividing Range than on the coast.

Damage to roads at Cooktown and Lions Den in north Queensland after Cyclone Jasper.Credit: Ergon Energy

The wettest day brought 714mm to Mossman in Queensland on December 18 in the wake of ex-tropical Cyclone Jasper.

All eastern state capitals were more humid than the long-term average for January. Sydney registered its highest dew point on record.

Climate Council chief executive Amanda McKenzie said the last northern summer had brought deadly heatwaves across the northern hemisphere and wildfires in Canada and Hawaii and the Australian summer had brought the seventh mass bleaching event on the Great Barrier Reef.

Scientists monitored 27 sites in the Great Barrier Reef and found moderate to severe coral bleaching.Credit: James Cook University, Centre for Tropical Water and Aquatic Ecosystem Research

“What’s been scary and fascinating is the ocean temperature being so high,” McKenzie said. “Just to put it in perspective, the ocean absorbs heat equivalent to five Hiroshima bombs every second, and [if it were isolated] that would be enough to boil Sydney Harbour every eight minutes, just from the sheer amount of heat going into the system.”

Summer was a mixed bag for the nation’s farmers.

Heavy rain and flooding damaged oyster farms on the NSW South Coast, preventing harvesting during the lucrative Christmas season. In Queensland, cyclones were devastating for many fruit and vegetable growers, damaging avocado, mango, lychee and banana crops.

But the grape growers of south-eastern Australia are expecting a bumper crop, and anticipate wine exports to China might resume in the coming months.

Matt Dalgleish, executive director for agricultural analysis firm Episode 3, said rain in December and January in eastern Australia had delayed the harvest of grains and seed crops such as wheat, barley and canola, affecting quality rather than yield. But overall, Dalgleish said the season had been better than the hot, dry weather farmers had expected from El Nino.

“By and large, the weather has been reasonably kind through the summer period,” Dalgleish said.

He said the recent bushfires in western Victoria were in an area with few large-scale commercial farms, and the timing was after most crops had been harvested.