According to The Age, Victorian Farmers Federation Egg Group president Meg Parkinson told the Ballarat Courier that a reduction of up to 15 per cent was fairly normal over a hot summer.

"But this heat we've had this year can certainly make that much worse," Ms Parkinson said.

"And the bird flu outbreak before Christmas in New South Wales also meant 400,000 chooks and 200,000 pullets were out of the system.

"It's affected everybody and has tightened up the market."

Ms Parkinson said chickens lost some weight during hot weather as they ate and drank less, so in addition to fewer eggs being laid, the eggs could be smaller.

Major suppliers including Coles, Woolworths and Ryan's IGA have assured customers there are plenty of eggs available.

"We've not had any difficulty with our eggs during the hot weather over the last four weeks," IGA national council chairman Ben Ryan said.

Family Homestead managing director Vesna Luketic said their production costs had shot up, while egg production had dropped considerably at her farm in Myrniong, which houses 15,000 free-range chickens.

"It's horrible, it has been the worst summer. The heat hasn't affected us like this in the past 15 years. It is going to be difficult to get through this," Ms Luketic said.

"Usually the chickens can bounce back reasonably quickly from the heat, but not when it's consecutive days like this."

Ms Luketic has been forced to change her farming practices to respond to the hot weather, by applying reflective paint to sheds, turning on misters and altering the chickens' food rations.

"Farming in this country is very difficult in the heat. We have little support from the government."