When I go camping during the summer, I usually take a thermometer with me. But to just get an estimate of the temperature on a warm summer night, all you need is your ears, and the chirping of a cricket.

The usefulness of a cricket as a thermometer is summarized in the following weather folklore:

"In a quarter of a minute, crickets cry in the night. This plus 40 will give you Fahrenheit."

In other words, count the number of chirps in a quarter of a minute - that is, 15 seconds - and then add 40. The number you get is an estimate of the air temperature in degrees Fahrenheit.

The credibility of this folklore is based on the fact that crickets are cold-blooded, so their metabolism rate is sensitive to temperature. Generally, as the temperature goes up, so does a cricket's rate of chirping. Crickets are particularly tuned to temperatures between 60^oF and 80^oF, a typical range for a summer night around here. The temperature estimates won't be perfect, but usually within a few degrees. The folklore actually is based specifically on the chirping rate of a particular type of cricket - the snowy tree cricket. Other types of crickets may not be as well calibrated.