Can Crickets Really Tell You the Temperature Outside?

cricket thermometer
How often a cricket chirps actually is related to air temperature!. Stickney Design/Moment/Getty Images

True or false: Crickets chirp faster when it's warm and slower when it's cold, so much so, that crickets can be used as nature's thermometers?

As wild as it sounds, this is one piece of weather folklore that's actually true!

How a Cricket's Chirp is Related to Temperature

Like all other insects, crickets are cold-blooded, meaning they take on the temperature of their surroundings. As temperature rises, it becomes easier for them to chirp, whereas when temperature falls, reaction rates slow, causing a cricket's chirp to also diminish.

Male crickets "chirp" for multiple reasons including warning off predators and attracting female mates. But the sound of the actual chirp is due to a hard rigid structure on one of the wings. When rubbed together with the other wing, this is the distinctive chirp you hear at night.

Dolbear's Law

This correlation between air temperature and the rate at which crickets chirp was first studied by Amos Dolbear, a 19th century American physicist, professor, and inventor. Dr. Dolbear systematically studied various species of crickets to determine their "chirp rate" based on temperatures. Based upon his research, he published an article in 1897 in which he developed the following simple formula (now known as Dolbear's Law):

T = 50 + ((N - 40) / 4)

where T is temperature in degrees Fahrenheit, and

N is the number of chirps per minute.

How to Estimate Temperature from Chirps

Anyone outside at night listening to crickets “sing” can put Dolbear's Law to the test with this shortcut method:

  1. Pick out the chirping sound of a single cricket.
  2. Count the number of chirps the cricket makes in 15 seconds. Write down or remember this number.
  3. Add 40 to the number of chirps you counted. This sum gives you a rough estimate of the temperature in Fahrenheit.

(To estimate the temperature in degrees Celcius, count the number of cricket chirps heard in 25 seconds, divide by 3, then add 4.)

Note: Dolbear's law is best at estimating temperature when tree cricket chirps are used, when the temperature is between 55 and 100 degrees Fahrenheit, and on summer evenings when crickets are best heard.

See Also: Animals & Creatures that Predict the Weather

Edited by Tiffany Means