An extreme heat wave in Kansas has killed thousands of cattle across the state, as citizens are warned to look out for signs of heat stroke.

At least 2,000 cows have been killed by the heat and humidity during the heatwave, the Kansas Department of Health and Environment told Reuters. This number comes from facilities and farmers that have asked the agency to help dispose of cattle carcasses. Other estimates put the number at over 10,000.

Veterinarian A.J. Tarpoff, who works with Kansas State University, told local news outlet KSCB News that the deaths were caused by the "perfect storm" of heat stress during the day, followed by higher than usual nighttime temperatures.

“Heat stress doesn’t happen all at one time," Tarpoff explained to KSCB News. "Cattle accumulate heat during the day, and then over the nighttime hours, it takes four to six hours for them to dissipate that heat. As long as we have a cooling effect at night, cattle can mostly handle the heat."

"Where we run into issues is where we have two to four days in a row of minimal nighttime cooling, and we start the day with the heat load we accumulated the day before still there."

Temperatures in many parts of the state went above 38°C (100°F) over the weekend, with humidity levels adding to the problem. 

Tarpoff added that deaths of cattle tend to begin around early June, as cattle haven't fully shed their winter coats. Temperatures will be roughly the same this weekend according to Drew Lerner, president of World Weather Inc, though cooling winds may provide better conditions for the state's cattle. 

Meanwhile, Brenda Masek, president of the industry association Nebraska Cattlemen warned cattle owners to keep a close eye on their stock.

"You can't say, 'Oh I checked them three days ago,'" she told Reuters. "When it gets hot, you've got be to out every day and making sure that their water is maintained."