Sailors long watched red morning skies as a rough sign of storms approaching later.

The longer version

This old saying has a real basis in the way weather systems move. In middle latitudes weather generally travels from west to east, so the sky to the west hints at what is on the way, while the eastern sky shows what has already passed.

A red morning sky means the rising sun in the east is lighting the underside of cloud to the west, where a wet system is approaching. A red evening sky suggests clearer air to the west instead. It is a rough indicator rather than a firm rule, and it works best where weather systems travel steadily in one direction.

Where this entry sits

Clouds, wind, rain, and storms shape daily life in ways that most people barely notice. This collection explains snow, lightning, rainbows, the turning seasons, temperature, the instruments forecasters rely on, and scraps of old weather lore. The full list sits on the Weather and Climate page, where every entry is listed in order.