Thus John Claridge in his preface to The Shepherd of Banbury's Rules: "The shepherd, whose sole business is to observe anything which has a reference to the flock under his care, who spends all his days and many of his nights in the open air under the widespread canopy of Heaven, is obliged to take particular notice of the alterations of the weather; and when he comes to take pleasure in making such observations, it is amazing how great a certainty he arrives at last by mere dint of comparing signs and events."
No one knows who the Shepherd of Banbury really was, or even if he ever existed as a person. He is one of those shadowy figures lurking in the wings of history, like "Monsieur de Marchiel", the Man in the Iron Mask, or the "person on business from Porlock" who so abruptly recalled a disappointed Coleridge from the delights of Xanadu to cold reality. All we know of the Shepherd is that Claridge claimed to have come across his writings, and published his alleged find in 1744.
The kernel of the Shepherd's wisdom was a set of 25 "hot tips" on weather forecasting, known ever since, and often quoted, as "The Shepherd of Banbury's Rules". In essence they encapsulate weather lore that was popular in England in the 18th century, and provide on-the-spot predictions based on commonly observed phenomena like recent weather patterns, the phases of the moon, and the predominating colours of the sky.
Meteorologists, as you might guess, view such home-spun weather wisdom with a jaundiced eye. But let me allow you to make up your own mind; here, for example, and for what they are worth, are the five rules the Shepherd quotes concerning mist:
Rule IX: If mists rise in low grounds, and soon vanish - there will be fair weather. Rule X: If mists rise to the hill tops - rain in a day or two. Rule XI: A general mist before the sun rises, near the full moon - fair weather. Rule XII: If mists in the new moon - rain in the old. Rule XIII: If mists in the old - rain in the new moon.
And for a long-range forecast, based on signs that may become apparent later on this month, you must go to the last two Shepherd's Rules. Rule XXIV: If the latter end of October be for the most part warm and rainy, then the winter will be frosty and cold. Rule XXV: If October and November be cold and with frost, January and February will be open and mild.