There are a lot of high-tech ways to predict the weather these days. But old sailors' proverbs have a lot of wisdom. Take, for example, the one about the rainbow.

"Rainbow in morning, sailors take warning
Rainbow toward night, sailors delight"

You guessed it. Following this rhyme might keep you out of the storm clouds.
Storm centers usually move from the west. Thus, according to Chapman Piloting and Seamanship, a morning rainbow would have to be viewed form its position already in the west, with the sun shining on it from the east. Since rainbows always form in a direction opposite to the sun, it would mean that rain is headed your way.

But if you see a late afternoon rainbow toward the east, it would tell you the rain has already past.

For more on the truths and falsehoods on old weather proverbs, check this Web site: http://www.wxdude.com/proverb.html