One Memorial Day weekend, an unexpected heat wave slammed the upper Midwest All-time temperature records shattered as the mercury climbed near 100 degrees Hardly a breeze stirred, and clouds of gnats swarmed every warm-blooded creature that ventured outside The combination proved deadly: the heat and gnats together killed a number of backyard chickens, including four of one keeper’s flock The lesson is a hard but important one Chickens tolerate cold far better than heat, and a sudden hot spell can be genuinely dangerous Here’s how to help your flock survive the heat, whether it arrives on schedule or catches