Extreme heatwaves threaten Australian food security, farmers warn

When record-breaking heatwaves hit parts of Australia over summer, it wasn't just people and wildlife that suffered.

For those trying to grow and supply the nation with fresh food, the extreme heat wiped out entire crops and highlighted a growing struggle for farmers.

And it is likely to become an even bigger challenge — not just in summer.

Researchers warn increasingly extreme heatwaves throughout the year are putting food security at risk, and more studies are 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.

"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.

"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.

"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.

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.

"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," Mr Atkin said.

"It means anything growing near the surface is going to be getting extremely hot."

Mr 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."

"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, Mr Atkin said they can and do occur at other times of the year when temperatures push above the normal during the day and night.

That includes during spring — a critical time for wheat flowering.

"Pollen is very susceptible to heat."

"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."

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.

Testing heat-tolerant wheat

Across Australia and the rest of the world, research is already underway.

Dr Crystal Sweetman is leading one study to improve heat tolerance in wheat, by growing different varieties in field trials across SA.

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.