Ummmm..... You have to specify the species of cricket. Each species has a
characteristic chirp factor.
Also are your degrees F, C or K?


This is from
http://www.noblenet.org/reference/crickets.htm

The formula for this is to count the number of chirps in 15 seconds and add
39 to calculate the temperature (degrees Farenheit.) If there are 30 chirps
in 15 seconds, the temperature should be about 69 degrees F. This formula is
said to be accurate within one degree. A variation is to count the chirps in
13 seconds, and add 40.
Sources:
"Cricket thermometers," Field & Stream, July 1993, Vol. 98 Issue 3, p21.



and from http://www.almanac.com/outdoors/crickets.php

we have this:

To convert cricket chirps to degrees Fahrenheit, count number of chirps in
14 seconds then add 40 to get temperature.
Example: 30 chirps + 40 = 70° F

To convert cricket chirps to degrees Celsius, count number of chirps in 25
seconds, divide by 3, then add 4 to get temperature.
Example: 48 chirps /(divided by) 3 + 4 = 20° C

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there's apparently a small descrepancy (1 degree) in the sources.