Extreme heatwaves have become a major threat to Australia's food supply, and not just in summer
Heatwaves during spring can have a detrimental impact on flowering wheat, causing significant losses. (ABC Midwest: Joanna Prendergast)
In short:
Heatwaves are becoming more extreme and frequent, making it harder to grow food crops.
Extreme temperatures are happening not just in summer, but also during critical spring flowering periods for crops such as wheat.
What's next?
Research is underway to discover and develop more heat-resistant crops, but scientists say more is urgently needed.
When record-breaking heatwaves hit parts of Australia over summer, it was not just people and wildlife that suffered.
The extreme heat also wiped out entire crops and highlighted a growing struggle for farmers with what is likely to become an even bigger challenge.
Researchers warn increasingly extreme heatwaves throughout the year are putting food security at risk, with more studies urgently needed to help growers adapt.
Anthony De leso manages Thorndon Park Produce, a family business north of Adelaide growing a wide variety of leafy vegetables and herbs.
During summer, his farm was hit by three extreme heatwaves that decimated delicate crops.
Anthony De leso grows spring onions, continental parsley, coriander and dill all year round north of Adelaide. (Supplied: Anthony De leso)
"The last heatwave we had was probably the worst in memory, because we had about three days of 45 degrees, and the days before and after were in the mid to high-30s, so there was no relief for us, the staff, and no relief for the crops," Mr De leso said.
"That was kind of like the last nail in the coffin for a lot of our crops.
"In the second heatwave, our coriander just decided 'That's it, I'm done'.
"It was easier for us just to rotary hoe in our existing crop and start afresh."
Mr De leso said lost income from ruined crops, combined with rising input costs, was taking a significant toll on his budget.
"In the past, I would have said, 'This is just what's going to happen and we have to take these hits every now and then,'" he said.
Coriander is one crop that is highly fragile and prone to heat stress. (Supplied: Anthony De leso )
"Since 2022 onwards, our input costs, everything's gone through the roof, so now to take these hits is a lot harder to do, to take a loss and just go on.
"There definitely has been discussions on what else we do differently: whether we focus on other crops, or put in some protected cropping in certain areas … because now when we have weather events, we definitely feel the losses harder than we used to."
More research needed
Australian National University professor of plant science Owen Atkin said extreme temperatures like those seen in January 2026 "breaks the biology" of plants, causing them to fail.
"Last January was a real wake-up call in regards to the types of temperatures we're likely to experience in the future,"Professor Atkin said.
Summer saw areas of South Australia and New South Wales break all-time temperature records, with parts of SA pushing close to 50 degrees in the shade.
Temperatures in January 2026 soared over multiple days across much of southern Australia. (ABC News)
"Some of my colleagues … were out in the field during that and they were recording temperatures [of] 65 degrees Celsius at the soil surface, and then 55 degrees Celsius about 10 centimetres from above the surface," Professor Atkin said.
"It means anything growing near the surface is going to be getting extremely hot."
Owen Atkin says heatwave temperatures can sterilise pollen and boil grapes on the vine. (Supplied: Owen Atkin.)
Professor Atkin said there were certain regions and crops more susceptible to heat damage, such as wheat, grapes and almonds.
"That area around Renmark is one which is a real issue. The Riverland, Mallee, Sunraysia area is one at risk," he said.
"In SA, we've got crops such as grapes, whether it be dried fruits, table grapes or viticulture for wine; they're all quite susceptible to heat.
"You're getting boiling, literally, of the berries on the vines, and that can cause problems to quality and quantity of yield … and affect the quality of wine that's produced as well."
Not just summer
While summer heatwaves are making headlines, Professor Atkin said they could and did occur at other times of the year when temperatures pushed above the normal during the day and night.
"We shouldn't think about heatwaves necessarily only being in the summer period because you can have unusually warm periods at other times of the year,"Mr Professor Atkin said.
That includes during spring, a critical time for wheat flowering.
Crops like wheat (pictured), grapes and almonds are more susceptible to heat damage. (ABC South East SA: Elsie Adamo)
"Pollen is very susceptible to heat," he said.
"You can get death of pollen and that ultimately leads to sterile flowers, so you don't get seeds being produced, yield being reduced in wheat, and that'll be something that occurs in other plants as well.
"And that could be just one day of heat.
"If you get an unusual heatwave in September, you can get … a 10 to 20 per cent reduction potentially in yield from a day's heatwave during that time of the year."
Heatwaves significantly impact crops like avocados. (ABC Riverland: Amelia Walters)
Professor Atkin said there was an urgent need to adapt and find ways to grow and protect crops from extreme heat.
That includes better heatwave predictions, strategies around crop canopies, misting, improved water access and irrigation practices, as well as plant genetics.
"My own view is that we have to use those techniques, particularly gene editing, and possibly in the future gene modification … so, GMO technologies," he said.
"We'll need everything in our toolkit in order for us to be able to have crops that are capable of handling the heat, which will be much more intense in the future."
Testing heat-tolerant wheat
Across Australia and the rest of the world, research is already underway.
Crystal Sweetman, associate professor of agricultural sciences at Flinders University, is leading one study to improve heat tolerance in wheat, by growing different varieties in field trials across SA.
Crystal Sweetman says plants are finding strategies to deal with extreme heat. (Supplied: Crystal Sweetman)
The international study aims to improve the yields of bread wheat during combined heat and drought conditions, by tapping into the cellular strategies plants already use.
"We're really interested in ways plants have developed some of their own nifty strategies to deal with some of these impacts of heat," Dr Sweetman said.
"We're learning more about these so we can understand processes already happening in plants, such that we can maybe identify similar processes in wheat or other crop species, and use them for breeding more heat-tolerant crop varieties."
She said the ongoing study had already provided some promising results, finding some wheat varieties that have been able to better protect themselves during extreme heat and drought.