What is the Origin of the “Red Sky in Morning” Warning?

What is the Origin of the “Red Sky in Morning” Warning?

“Red sky at night: sailors’ delight.

Red sky in morning: sailors take warning.”

This little rhyme is one of the first lessons any of us get about how to predict the weather. Just where did it come from? Is it reliable? If it is, why? For the answers to these questions, keep reading.


The observation that a red sky in the evening pointed toward pleasant weather, whereas red skies at dawn meant just the opposite, has been a part of the human experience for thousands of years. Jesus referred to the phenomenon in Matthew 16:2-3:

“When it is evening, you say, ‘It will be fair weather; for the sky is red.’ And in the morning, ‘It will be stormy today, for the sky is red and threatening.’ You know how to interpret the appearance of the sky, but you cannot interpret the signs of the times.”

How reliable is this ancient saying? It is actually pretty dependable — at least if you live in a part of the world where weather systems come from the west. Red skies at night mean dust and small particles are trapped in the atmosphere because of a high-pressure system. These particles scatter the blue light coming from the sun, allowing only the red light of the color spectrum to breakthrough. Since high-pressure systems typically mean fair weather, the reddish hue is a pretty accurate predictor of the next day’s pleasant weather.

If you see red skies in the early morning, the color is caused by light from the clear skies over the horizon to the east illuminating the undersides of moisture-bearing clouds. The saying assumes that more such clouds are coming in from the west.

While there are always exceptions, it would certainly be worth your time to take a glance toward the sky in the morning and the evening. Not only could you be enriched by a beautiful view, but you may get a clue about whether you should carry your umbrella. Visit Commonplace Fun Facts for more entertaining and informative articles, videos and more.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.