In the 18th century, families relied on almanacs to help them make many weather and seasonal decisions, such as when they should plant their crops or travel. However, almanacs only gave a long-term idea of what the weather might be based on weather in the past. If someone wanted an immediate weather forecast, weather accounts and “indicator journals,” which used observations of nature, were prolific.
Are these weather indicators old wives tales or were 18th century weather enthusiasts on to something?
Some 18th century weather predictors:
-"You May expect some Rain, or Snow, according to Season of the Year, either on the third or fourth Day before, or on the third or fourth Day after every Change or Full of the Moon, in the whole Year; as also, at or near the Time when the Moon enters every first or last Quarter."
-"If there appear a Circle about the Moon, you may expect stormy Weather to follow shortly after."
-"If the Moon change on a Sunday, it is almost a certain Sign of a Flood before the next new Moon."
-"If the Sun set under a thick black Cloud, it is almost a sure Sign of some Rain the next Day."
-"If a Rainbow appear in the Morning, it is a Sign, for the most Part, of several Showers of Rain before Night."
-"When the Wind keeps varying much, from one Quarter to another, you may expect Rain in twenty-four Hours."
-"If there be no Dew in a still Summer's Morning you may expect Rain before Night, sometimes before Noon."
-"If the Smoke from the Chimnies, instead of ascending, fall to the Ground; you may expect Rain within twenty-four Hours, frequently sooner. 
-"The Crows flocking together in large Flights, holding their Heads upward as they fly, and crying louder than usual, is a Sign of Rain, as is also their stalking by Rivers and Ponds, and sprinkling themselves."
-"When Sheep leap mightily, and push at one another with their heads [it indicates rain.]"
-"When Cats rub their Heads with their Forepaws (especially that Part of their Heads above their Ears) and lick their Bodies with their Tongues[it indicates rain.]"
-"It has been the Observation of those that have had many Years Experience of the Weather, That when the Wind in the Summer Time has been South 2 or 3 Days, and it grows very Hot, and when you see Clouds arise with great white Tops like Towers, as if one cloud were on the Top of another, and join'd together with Black on the nether Side, that then it is like to be Thunder and Rain suddenly in many Places." 
Sunny or Hot Weather
-"If the Clouds appear of a scarlet Red at or near the Setting of the Sun, it is a sure Sign of fair Weather..."
-"In a hazy Summer's Morning, when you see many Spider-webs upon the Grass, Trees, &c. you may expect it will clear up, and be hot, in general, before twelve o'Clock."
-"I have observ'd that many, if not most of 'em do expand their Flowers and Down in Warm Sun-shiny Weather, and again close them towards Evening, or in Rain, especially at the Beginning of Flowering, when the Seed is young and tender, It is manifest in the Down of the Dandelion..." 
-"If the Mist [in the mornings] continues many Days, as it frequently does in November and December, I think it is a sure Sign of much Rain or Snow falling in the Winter."
-"Clouds like Woolly Fleeces appearing high and moving heavily; the Middle a Darkish Pale, and the Edges White, carry Snow in them..." 
I think I'll go outside and check the "down" of my dandelions. I knew I was growing them for some reason. :)
 Allen Hall, Observations on the Weather (Lincoln: Drury's Office, 1788), 10-21.
 John Pointer, A Rational Account of the Weather: Shewing the Signs of its several Changes and Alterations, together with the Philosophical Reasons of them (Oxford:S. Wilmot, 1723), 3-5.
 Pointer, A Rational Account, 35.
 Hall, Observations on the Weather, 13-21.
 Pointer, A Rational Account, 37.