In 1897, physicist Amos Dolbear discovered that you can estimate the temperature by counting a cricket’s chirps!

Crickets are cold-blooded, which means their body temperature changes with the weather. When it’s warmer, they chirp faster. When it’s cooler, they chirp more slowly.

Dolbear found a simple rule: count the number of chirps you hear in 15 seconds and then add 40. The answer gives you an estimate of the temperature in degrees Fahrenheit (°F).

For example, if a cricket chirps:

This rule works best with the snowy tree cricket, which lives throughout most of the United States.

This method works best when temperatures are within the cricket’s normal living range, between 55°F and 100°F.