You know how when it gets really hot, you just feel crazy, or stupid… or both! The weather being “stupid hot” is just not a silly saying, it's actually a real thing. 

And scientists have proven it, with the help of our animal friends. 

For example, on a blazing hot day in South Africa, female southern pied babblers can’t think straight. The medium-sized black-and-white birds are trying to get at tasty mealworms behind a see-through barrier. On cooler days, the birds can quickly figure out that all they have to do is go around the small wall of plastic. But when the mercury goes up, the birds just keep stubbornly pecking at the barrier.

That experiment is part of a growing body of research showing that animals get their minds muddled during heat waves. When it’s hot outside, birds struggle to learn, dogs bite more often, goat-like chamois pick fights.

If the animals can’t stay alert enough to find food or avoid predators, their chances of survival go downhill.

With climate change making heat waves more common, such cognitive impairments across the animal kingdom could ripple through entire ecosystems, putting already fragile species at greater risk. If pollinators forget which flowers to visit, crops and wild plants may fail. If birds can’t find food as easily, their young may not survive. And on a warming planet, a sharp mind is particularly vital.

Birds, for example, spend less time looking for food and feeding their young; they even sing less. Instead, they’ll sit around for hours with wings spread to dissipate the heat, and pant with their beaks wide open. Some animals retreat to shade or hide in cool burrows—again, skipping meals. Bees, meanwhile, splash their faces with droplets of water midflight when the weather is sizzling. This way, “they get convective cooling for their brain.”

However, it's not just animals that tend to behave differently in the heat waves. Humans do as well. When it’s hot, people have trouble making decisions, and their memory suffers. For students at schools without air conditioning, a school year just one degree Fahrenheit hotter reduces test scores by 1 percent, a study found.

So next time it is hot out and you are not feeling quite yourself… Just blame the weather!