Red Sky at Night: Weather Sayings and Their Meanings

Have you ever heard the adage, “red sky at night, sailor’s delight”? Read on to learn about the science behind this and other common weather folklore.

Long before meteorologists reported the weather, people made forecasts based on their observations of the sky, animals, and nature. Much of the traditional weather lore is surprisingly accurate. 

Try it out and see for yourself!

“Red sky at night, sailors delight. Red sky in morning, sailors take warning.”

Where the Saying Came From

Sailors and farmers relied on this weather saying to navigate ships, plant crops, and plan activities. It has been a common adage through the ages!

• In the Bible, there is a passage in which Jesus says, “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.’” (Matthew 16:2–3)
• In his poem, “Venus and Adonis,” William Shakespeare, also wrote about the red sky: “Like a red morn that ever yet betokened, Wreck to the seaman, tempest to the field, Sorrow to the shepherds, woe unto the birds, Gusts and foul flaws to herdsmen and to herds.”

What Science Says

Do you see a red sky at night? That means the Sun is setting in the west. We see red (and not other colors) because only the longer wavelengths (red and orange) can pass through our atmosphere, which is filled with dust and pollution. When there is a high-pressure system, the air sinks even further, creating a more vibrant red. 

High pressure, however, means dry, clear weather is coming. Weather moves west to east, which means the high pressure is moving east. The good news is not only that we see pretty sunsets but also enjoy dry, fair weather. Clear weather would “delight” a sailor.

Conversely, a reddish sunrise means that dry air from the west has already passed over us on its way east, clearing the way for a storm to move in. The high-pressure air has most likely already passed from the west to the east, and an area of low pressure may follow. Low pressure usually brings clouds, rain, or storms, a warning for sailors that bad weather is moving in.

Does the Saying Hold True?

Yes, this phrase makes meteorological sense.

• If the evening sky is especially red, this means that there is a high-pressure system, and the sunrays must travel through a higher concentration of dust particles. This means that stable air is coming in from the west. Good weather is on its way.
• If it’s a red sky in the morning, that means the high-pressure system has passed, and a low-pressure system is moving in. Rain and bad weather are on their way. See more weather proverbs about rain and clouds!

Note: While weather generally moves west to east, sometimes storms can move from south to north. In those cases, this saying wouldn’t apply!

Other Weather Sayings and Their Meanings

“The higher the clouds, the finer the weather.”

If you spot wispy, thin cirrus clouds up where airplanes fly, expect a spell of pleasant weather.

Keep an eye, however, on the smaller puffy clouds (cumulus), especially in the morning or early afternoon. If the rounded tops of these clouds, which have flat bases, grow higher than their widths, there’s a chance of a thunderstorm forming.

“Clear Moon, frost soon.”

When the night sky is clear, Earth’s surface cools rapidly as the heat from the day radiates back into the atmosphere. 
There is no cloud cover to keep the heat in. 

If the night is clear enough to see the Moon and the temperature drops enough, frost will form. Expect a chilly morning!

“When clouds appear like towers, the Earth is refreshed by frequent showers.”

When you spy large, white clouds that look like cauliflower or castles in the sky, there is probably lots of dynamic weather going on inside. Innocent clouds look like billowy cotton, not towers. If the clouds start to swell and take on a gray tint, they’re probably turning into a thunderstorm. Watch out!

“Rainbow in the morning gives you fair warning.”

A rainbow in the morning indicates that a shower is in your near future. Why? The Sun is in the east when it rises. We know that weather moves from west to east. So, if you see a rainbow near sunrise in the east, that means the rain is coming your way!

“Ring around the Moon? Rain or snow real soon.”

Clouds that appear as high as the Moon are made of ice crystals. These cirrostratus clouds appear as thin sheets that stretch across the sky and indicate the approach of rain or snow.

When these cirrostratus clouds pass in front of the Moon, the ice crystals catch the light of the Moon and act as prisms, forming a white or colorful ring around the Moon. 

Thus, a ring around the Moon often indicates cirrus clouds. The warm front is advancing with an associated area of low pressure, and precipitation in the form of rain or snow may follow!

“Mackerel sky, storm is nigh.”

If you have ever seen very high, rippled clouds that look like fish scales, sailors call it a “mackerel sky” and indicate that a storm may follow.

A mackerel sky refers to high-up cirrocumulus clouds. These clouds often precede an advancing warm front that will bring winds and precipitation. See more about identifying clouds in the sky.

“A year of snow, a year of plenty.”

Snow that blankets the land has many benefits! First, it kills a lot of plant pests. Second, it delays the blossoming of fruit trees until the season of killing frosts is over. Third, it prevents thawing and freezing cycles.

Finally, have you ever heard the expression, “snow is a poor man’s fertilizer”? Snow slowly releases nitrogen, providing healthier soil for growing!

“Rain foretold, long last. Short notice, soon will pass.”

If you find yourself toting an umbrella around for days “just in case,” rain will stick around for several hours when it finally comes. The gray overcast dominating the horizon means a large area is affected. Conversely, if you get caught in a surprise shower, it’s likely to be short-lived.

Observe the sky and see if these weather proverbs work for you. Do you know of any others? Tell us in the comments below!