There is some truth to the rhyme “Red sky at morning, sailors take warning, red sky at night, sailors’ delight”.
The trick is to look at the part of the sky where the sun isn’t, not into the sunset but to the east.
Both sunrise and sunset are reddish, as a rule, because of what happens to the light from the sun as it goes through the atmosphere at a low angle.
It scatters away most colors, so all that is left is reddish hues.
But if the sky is red in the part of the sky away from the sun, some rough forecasts can be made.
The red sky rule applies to weather patterns that move from west to east.
The idea is that sunlight interacting with additional water vapor in the part of the sky away from the sun leads to red and orangeish hues, so a red sky in the west in the morning means a storm system creating the hues is moving your way.
If it is red at night looking off to the east, the storm system or moisture to the east is moving away from you.