
In the panel you can read:
Wet Stone: Rainy
Dry Stone: Dry weather
Shadow in the ground: Sunny
White stone: Snowing
You do not see the stone: Foggy
Shaking stone: Windy
Stone up and down: Earthquake
The stone is no longer there: Tornado
It reads in the Panel Instituto de Meteorologia (Portuguese Weather Service), but I am sure It is true.