The earliest account in print is in A Vocabulary of the Anglo-Manx Dialect, compiled by A. W. Moore with the co-operation of Sophia Morrison and Edmund Goodwin and published by Oxford University Press in 1924, fifteen years after Moore's death. Under Caillagh it names her the Caillagh-ny-faishnag, the hag of the prophecies, who was also called the Caillagh-ny-brasnag, the hag of the faggots, and the Caillagh-ny-groamagh, the hag of the sulks. She was an Irish witch who had been thrown into the sea to drown, and who floated to the Isle of Man and came ashore on Candlemas morning. The day was bright, and she set to work to gather brasnags, sticks for firing, to light a fire and dry herself. Under Breeshey, St Bridget, the same book gives the weather rule that went with her. Every ditch had to be full of rain or snow on St Bridget's Day, so that the old caillagh could not gather the brasnags. If she could lay in a stock of firing on that day there would be bad weather in the spring, but if she could not gather the brasnags there would be fine weather.

W. Walter Gill, in A Manx Scrapbook of 1929, recorded a different story of her, gathered in the parish of Patrick and printed in his place-lore of Malew. Near the top of Ballagilbert Glen, on the Silverburn below South Barrule, is a small depression called Caillagh ny Groamagh, the Old Woman of the Gloominess, into which she fell, or which she scooped out by falling, when trying to step from the top of Barrule to the top of Cronk yn Irree Lhaa. The impression of her heels and her backside were said to be plainly visible in the soil. Gill set beside this the Irish Caillagh who broke her neck jumping from height to height among the Lough Crew hills, and the Scottish Cailleach Bheur, who is the personification of bad weather itself. Apart from her fall, the Manx Caillagh was known for her influence over the weather, and it is as a weather figure that she survives.

Her alternative name, Gill explained, was Caillagh ny Fai'ag, which is a pronunciation of Faihtag, prophecy or prediction, and he thought that a third old woman, the Caillagh ny Ghueshag who foretold things, was much the same personage as far as such shadowy abstractions could be classified. Laa'l Vreeshey, St Bride's Day, the first of February and the first day of the Manx spring, was the day the Caillagh came out. If the weather was fine she came out to gather sticks to keep her fire going for the rest of the year. If it was wet and stormy she stayed in, because the sticks would be wet. From this the rest of the season was known, but contrariwise. If the day was fine the summer would be wet, because she would not need to come out again, and if the day was bad she would see to it that fine weather followed, for her own sake. Gill's informant added that there were people who had seen her flying over in the shape of a big bird, carrying the sticks in her mouth. What kind of bird was not known, but Cronk yn Irree Lhaa was thought to be her customary home.

The weather rule is older than the figure in the printed record. A. W. Moore, in 1891, gave the Manx sayings for St Bridget's Day without any old woman attached to them. If Bridget's Feast-day was white, every ditch would be full, meaning a wet mild spring after snow, and as long as the sunbeam came in on Bridget's Feast-day, the snow would come before May Day, meaning a cold spring after a mild one. He noted that Candlemas, the following day, had taken over the same prognostics as St Bridget had been forgotten, and that the belief that fair weather on that day meant a long winter was universal throughout Christendom. The Caillagh, then, is the Manx form of a rule about the first days of February that is known across Europe, given a person, a fall, a nest of sticks and a hill of her own. Gill also noted a Danish version of the same weather-controlling old woman reported in the journal Folk-Lore in 1891, and a German saying that women rule the weather in February.