The American-English proverb open and shet, sign o’ more wet, and its variants, mean that alternately sunny and cloudy conditions usually indicate rain.
This proverb seems to be chiefly used in New England, an area on the north-eastern coast of the USA, comprising the states of Maine, New Hampshire, Vermont, Massachusetts, Rhode Island and Connecticut.
The adjective shet is a variant of shut. It was perhaps in order to provide a rhyme for the adjective wet that the variant shet was chosen in the proverb.
These are, in chronological order, the earliest occurrences of the proverb open and shet, sign o’ more wet, and variants, that I have found:
1-: From Education by Bumps, the review of The Scientific Basis of Education: Demonstrated by an Analysis of the Temperaments and of Phrenological Facts, in Connection with Mental Phenomena and the Office of the Holy Spirit in the Processes of the Mind: In a Series of Letters, to the Department of Public Instruction in the City of New York (New York: A. S. Barnes & Co., 1868), by John Hecker—review published in The Nation: A Weekly Journal devoted to Politics, Literature, Science, and Art (New York: E. L. Godkin & Co.) of Thursday 8th October 1868:
Mr. Hecker gratifies and startles us by the information that there are four leading temperaments—the nervous, sanguine, bilious, and lymphatic—in which the functions of the nervous system, the lungs, the liver, and the stomach respectively predominate. His profound physiological researches have also taught him that the nervous temperament is apt to have the hair brown and silky, while the sanguine has it ruddy, the bilious coarse and dark, and the lymphatic dull and flaxen. The nervous temperaments also learn quickly and forget quickly, while the bilious learn slowly and remember tenaciously; nervous people are apt to be thin, and lymphatic people fat; the latter like to sit still, while the sanguine people prefer to be moving about in the open air, and the bilious people court seclusion. And so forth; all of which, in point of scientific value, reminds us of the old woman’s meteorologic aphorism,
“Open and shet,
Sign of more wet.”
2-: From We Girls: A Home Story (Boston: Fields, Osgood, & Co., 1870), by the U.S. author Adeline Dutton Train Whitney (1824-1906):
“I wish we had n’t bought the new carpet now,” said mother. “And what shall we do about all those other great rooms? It will take ready money to move. I’m afraid we shall have to cut it off somewhere else for a while. What if it should be the music, Ruth?”
That did go to Ruth’s heart. She tried so hard to be willing that she did not speak at first.
“‘Open and shet is a sign of more wet!’” cried Barbara. “I don’t believe there ever was a family that had so much opening and shetting! We just get a little squeak out of a crack, and it goes together again and snips our noses!”
3-: From A Chirp from a Conservative Cricket, by Laura D. Nichols, published in Old and New (Boston: Roberts Brothers, Lee and Shepard) of December 1874:
I purpose for old acquaintance’s sake, and as an addition (not unworthy) to our classical literature, to set down in order some of these old-fashioned pearls of weather-wisdom, for which our fathers dived into rough seas of experience, and which they carefully strung on threads of memory, and transmitted from generation to generation.
The first I remember to have heard was repeated to me by my gentle grandmother, and, being rhymed, was never forgotten:—
“Red sky at night,
Red sky in the morning,
Sailors take warning.”
In inland districts, “shepherds” is substituted for “sailors;” and by reading Matt. xvi. 2, 3 *, we see that the saying is at least as old as the Bible. It is certainly one of the most infallible of signs, and is sometimes more elaborately and fancifully rendered as follows:—
“Evening red, and morning gray,
Speed the traveller on his way:
Evening gray, and morning red,
Bring down showers upon his head.”
My next acquisition was from my father, when I was eagerly hoping a storm would clear away, and allow me to go on some longed-for excursion. “If you can find a patch of blue sky in the west, as big as a squaw’s cap, you may get ready to go,” said he; and though I was so young that I had to ask my nurse which was west, and what a squaw might be, I never forgot the saying, and even resented, as an impertinent innovation, the “leather apron” or “Dutchman’s breeches” which some substitute for the squaw’s cap.
“Open and shet, sign o’ more wet,” was imparted to me, also at an early age, by a weather-wise but otherwise ignorant servant; and the equally rude rhyme, “Southerly glim, sign of a wet skin,” I heard in one of my first visits to the sea. A critical friend suggested the rendering, “Southerly glimmer, sign of a wet sinner;” but I never heard that the Gloucester fishermen adopted it.
* This is from the gospel of Matthew, 16:2-3, in the King James Version (1611):
2 When it is euening, yee say, It will bee faire weather: for the skie is red.
3 And in the morning, It will be foule weather to day: for the skie is red and lowring.
4-: From a letter that the U.S. philosopher and historian John Fiske (1842-1901) wrote on Thursday 13th June 1878 from Cambridge, Massachusetts—as published in The letters of John Fiske. Edited by his daughter Ethel F. Fisk (New York: The Macmillan Company, 1940):
Passed Sunday at Tom Perry’s at Kingston going down Saturday afternoon. Walked from Kingston station missing the road, to near South Duxbury. Had a ride on an ox cart that came along and finally penetrated a trackless forest and came out at Perry’s. Delicious evening of roaring wood-fire and dank dripping rain on the grape leaves outside. Sunday “open and shet, sign o’ more wet”. Loafing, lobsters, Jersey cows, pine woods, appetizing salad, onion, omelette, absurd French book, and tobacco smoke; a genial day—not omitting hard cider.
5-: From Brownie Sandford; Or, The Recovered Pearl (Chicago: Henry A. Sumner and Company, 1881), by Carrie L. May:
Brownie gave up all hope of going out when Hannah said that it was to be no day for voyaging, and she had not thought of the weather since Ruth came in, but when they left the playroom, there was a little patch of sunshine on the hall floor; the rain had ceased falling and the clouds were breaking.
“Why, Hannah,” said Brownie, “it is almost pleasant, the sun is out.”
“Open and shet, is a sign of more wet,” returned Hannah, without leaving her work.
“But it is not open and shut,” said Brownie, “it is all blue sky.”
Hannah went to the door and consulted the weather-vane.
“The wind is shifting,” she said, “but it is backing in, and that’s a sign fair weather won’t stand, but I reckon it will hold, by the looks.”
6-: From South-County Neighbors (Boston: Roberts Brothers, 1887), by Esther Bernon Carpenter (1848-1893):
The warm yellow light in the west still lingered, bathing the whole stretch of country in a transfiguring glow which held the eye with almost the same effect of a sudden revelation of new beauty in familiar scenes as is afforded by the magical touches of a light snowfall; though the darkening clouds constantly lowered upon the horizon, fast obscuring the parting smile of the many-minded April day.
“Open an’ shet, sign o’ wet,” sapiently commented Brandywine Spears, who, while awaiting the call to supper, was whittling at a small block intended as a wheel for the toy go-cart which he was rudely fashioning for his youthful son.
7-: From Their Canoe Trip (Boston: Roberts Brothers, 1889), by Mary Prudence Wells Smith (1840-1930):
Presently the lake’s smooth surface began to dimple with pattering raindrops from the dark clouds overhead. This was the first of a series of driving showers, following one another all day, with brief intervals of watery sunshine, which, instead of encouraging him, reminded Gifford of Bridget’s favorite weather prediction,
“Open and shet,
A sign of more wet.”
8-: From Tea Tephi in Amity. An Episode, by A. B. Ward, published in Harper’s New Monthly Magazine (New York: Harper & Brothers) of October 1890:
She found Mrs. Stubbs standing with arms akimbo, examining the weather. “Never knew such a spell,” she shouted, as the girl entered the kitchen. “Miss Teethy, you won’t think much of Amity if it serves you like this. But I tell you it’s fine when the sun doos come out—to stay, I mean. It’s been ‘open and shet, sign o’ wet,’ for three days.”
9-: From Weather Forecasts, published in The Evening Star (Washington, District of Columbia) of Saturday 15th November 1890:
But weather has another errand in the universe, a more personal one, affecting a comparatively few people, but each one in himself such a part or parcel of the business of soothsaying that were weather abolished tomorrow by law he would find himself with half of his occupation gone. These men are the weather prophets, who labor daily in order that this demand for futuritive knowledge on the part of an insatiable public may be partially complied with. But they are but the exponents of a tendency that has always existed in the minds of mankind, a tendency that has crystallized itself into records in the form of quaint sayings and distiches that bear some clever allusion to the weather probabilities of the next few hours. Farmers and sailors are the principal contributors to this form of literature and the “weather forecasts” that are thus made standard guides to public health. “Open and shet, sign o’ wet!” There is one born of the potato patch and the corn field. Here is one that smacks of the salt, salt sea: “A red sky at night is the sailors’ delight; a red sky in the morning is the sailors’ warning.” Dew drops on cobwebs are taken as efficient barometric signals of rain.
10-: From The Thunder Storm, in Arcadian Days: American Landscapes in Nature and Art (Boston: Estes & Lauriat, 1891), by William Howe Downes (1854-1941):
I suppose that nobody has ever illustrated showery weather so faithfully as Constable—weather which means “take your umbrella with you when you go out today,”—or in other words, the sort of weather alluded to in the classic legend:—
“Open and shet,
The day’ll be wet.”
11-: From Folk-Lore from Maine, by Gertrude Decrow, published in The Journal of American Folk-Lore (Boston and New York: Published for the American Folk-Lore Society by Houghton, Mifflin and Company, 1892):
Open and shet, sign of more wet.
12-: From a list of seventy-five sayings given by “a little, old-fashioned New England lady, […] about seventy years old”, as published in The Indianapolis Journal (Indianapolis, Indiana) of Sunday 3rd February 1895—reprinted from The Boston Herald (Boston, Massachusetts):
Open an’ shet,
Sign of a wet.
13-: From Contributions to the New England Vocabulary, by Frederic D. Allen, published in Dialect Notes. Published by the American Dialect Society (Norwood, Massachusetts: Printed by J. S. Cushing, 1896):
The following words and phrases are in use in Portsmouth, N.H., a town which preserves a good many old-time characteristics of speech, custom and architecture in a remarkable degree, and which enjoys, I think, the special distinction of being the only place in this hemisphere where Guy Fawkes and the Gunpowder Plot are still appropriately celebrated.
Many of these expressions are current elsewhere in New England, but the writer has never met with any of them outside of New England. Those marked with a star (*) are peculiar to Portsmouth so far as he can find out.
*light and shut: of the weather. ‘It lights and shuts,’ that is, the sun peeps out at intervals. The common New England maxim is “Open and shet’s a sign of wet.”