I finally looked it up.

“Usually, weather moves from west to east. In the mid-latitudes, the prevailing winds are westerlies. This means storm systems generally move in from the West.…

Red sky at night, sailors delight When we see a red sky at night, this means that the setting sun is sending its light through a high concentration of dust particles. This usually indicates high pressure and stable air coming in from the west. Basically good weather will follow.

Red sky in morning, sailor’s warning A red sunrise can mean that a high pressure system (good weather) has already passed, thus indicating that a storm system (low pressure) may be moving to the east. A morning sky that is a deep, fiery red can indicate that there is high water content in the atmosphere. So, rain could be on its way.…

In the Bible, (Matthew XVI: 2-3,) Jesus said, ‘When in evening, ye say, it will be fair weather: For the sky is red. And in the morning, it will be foul weather today; for the sky is red and lowering.’”

https://www.loc.gov/rr/scitech/mysteries/weather-sailor.html

Another source: https://scienceblogs.com/startswithabang/2009/09/14/q-a-sailors-delight-fact-or-fi/

Photo from: https://simple-pleasures.org/2013/09/05/red-sky-orange-sky/