Weather Folklore

All of the pieces of folklore included in this article were written before the invention of modern forecasting equipment. However all of them are backed by current scientific knowledge, and can be used with a certain degree of accuracy to predict everyday weather.

Red skies in morning sailors take warning,
Red skies at night sailors delight.
-The Bible (Mathew 16:2,3)

This is proven true by the sun and the movement of weather fronts in the mid latitude regions, (unfortunately it is somewhat less accurate everywhere else, but still works to a degree) and is justified like this: Weather systems move from east to west, so when the sun is setting, the clouds in the west are more brightly lit, thus showing the weather that has already past as red. In the morning the sun rises in the east, and shows the clouds in the east which will be coming in as red, predicting weather to come.

Rainbow to windward, foul fairs the day,
Rainbow to leeward, damp runs away.

This is also proven by weather systems being moved by the wind. Rainbows are formed by light being refracted through a clear substance (a glass prism, water, etc.) This means that where the rainbow is there are water droplets in the air. So if the rainbow has formed on the side the wind is blowing to (the leeward side), that means that the rain is being blown away from you. However, if the rainbow formed the side the wind is blowing from (the windward side), then the wind is blowing the storm toward you.

Dry grass before the light,
Look for rain before the night,
When the dew is on the grass,
Rain will never come to pass.

Land cools off faster at night than water, and dry air has a dew point that is much lower than moist air. Since the air near the surface quickly takes on the properties of the surface, in this case dryness, the moisture in the air is being pushed upwards to the cooler upper reaches. When the air cools and the moisture condenses you have rain. However when the surface is wet dry air goes up and instead of rain you have dew.

Information from:
Weather: How it Works and Why it Matters
By:Arthur Upgren and Jurgen Stock (Perseus Publishing 2000)
