Red Sky at Night, Shepherd’s Delight? Unpacking Weather Folklore and the Science Behind It.

Before modern forecasting, people relied on observing nature to predict weather, passing down knowledge through rhymes, proverbs, and folktales. These weather sayings vary in accuracy, and understanding their scientific basis (or lack thereof) offers a unique perspective.

"Red sky at night, shepherd’s delight. Red sky in morning, shepherd’s warning,"

This common saying demonstrates a connection to atmospheric science, especially in mid-latitudes where weather moves west to east. A red sunset is caused by sunlight through dust in dry air, associated with high-pressure and stable weather. A red sunset in the west suggests approaching clear weather. Conversely, a red sunrise in the east indicates the clear air has passed, and a low-pressure system, possibly bringing precipitation, may be coming.

"When dew is on the grass, rain will never come to pass. When grass is dry at morning light, look for rain before the night"

This also has an observational basis. Dew forms on clear, calm nights, linked to high-pressure and stable weather. No dew can indicate cloud cover or wind, often associated with approaching low-pressure systems and rain.

"Halo around the sun or moon, rain or snow comes very soon"

Describes another accurate piece of folklore. Halos are created by light refracting through ice crystals in cirrostratus clouds, often preceding warm fronts or low-pressure systems, both associated with precipitation.

However, not all folklore is accurate. The Groundhog Day prediction (shadow on February 2nd means six more weeks of winter) lacks scientific support. Groundhog behavior isn't a reliable indicator. Similarly, attributing weather prediction to animal behavior, like cows lying down, is generally more superstition. Although a drop in air pressure could lead to some changes in animal behaviour.

Although not accurate, reliable or convenient, many weather sayings are based on the act of making observations. The act of accurately observing the current weather, along with the deep knowledge of previous weather patterns and the science behind meteorology are the fundamental building blocks of the most advanced weather models of today.

OpenWeather is at the forefront of some of the most advanced and accurate science-based forecasts today. We do however acknowledge the history behind meteorology, and the trailblazers who observed, analyzed and understood the seemingly infinitely complex weather patterns that exist around the world.