There is a lot of truth with weather sayings. For example:
Red skies at night, sailors delight.
Red sky in the morning, sailors take warning.
These refer to the fact that the sun rises in the east (morning) and sets in west (night). The color of the sky with the sun shining through tells us a little about the clouds and other atmospheric conditions. And for us in the mid-latitudes, weather travels west to east due to the westerly wind flow and the pressure belts.
What other sayings of weather have you used?