Wetterfrosch

Etymology
From 🇰🇲. Some frogs climb up vegetation in warm weather, so it was erroneously believed that the same behaviour could also predict warmth.

Noun

 * 1) A frog kept in a jar with a small ladder; when the frog climbed up the ladder, this was seen as an indication of warmer weather in the following days.
 * 2)  A meterologist, weatherman.

Usage notes

 * The custom was common until the first half of the 20th century and, though no longer practiced, is still generally known in the German-speaking world.