Well, the weirdest way possible is to listen to a cricket's chirp then apply some simple arithmetic—but it only works in Fahrenheit.
Seriously.
Crickets have chemical reactions occurring in their body, like all living organisms, that allow muscles to move and contract, causing them to chirp.
Since crickets are cold-blooded insects, they take on the temperature of their surroundings, which means the temperature directly affects how the chemical reactions are occurring. This is called the Arrhenius equation.
Wait for a day with a temperature between 55 and 100 degrees F and pick out a single cricket's chirp. Count how many times it chirps in 14 seconds and add 40. This is the temperature according to the equation printed in the Farmers' Almanac.
