Contending with temperatures hitting a sweltering 38 to 40 degrees Celsius in the shade during the last two months, cows in the northern valleys and Lower Galilee have cut their milk output by 25% or more, farmers say.

The drop in output, a common summer occurrence, has also been felt on the coastal plains and at higher elevations, but by a more moderate 10% to 15%. Farmers everywhere, however, say the decreased output is lasting far longer than usual this year.

Gilad Kramer, who runs a 150-head family dairy farm in Yavne'el, said that despite the cooling system he has installed, his milk production has fallen 28%, costing around NIS 3,700 a day in lost revenues. He explained that cows can't perspire and lack any natural way to cool themselves off. The distress this causes them causes them to reduce the amount of milk they produce.

According to Kramer, production typically drops about 25% during the hottest part of the summer, but seldom for longer than a month.

In early September 2010, when Israel suffered a particularly hot summer, milk disappeared from store shelves, and emergency supplies totaling about 1,500 tons of powdered milk imported duty free from the United States couldn't make up the shortfall. The country also experienced its worst ever butter shortage to date, lasting well into November that year.

This year, dairy product shortages at supermarkets are not on the horizon yet. When shortages do occur, however, they typically begin with products subject to price controls. Retail margins on these products are narrower than on uncontrolled items.