The word dreich has only made one appearance on EL&U, that I can find, and it was a questionably brief appearance in answer to a single word request.
This unassuming word did, however, top the polls five years ago in a Scotsman survey to find the most favoured word in the Scots language by its own speakers.
Merriam Webster, at least online, has a minimal note on dreich which states only 'dreary' and misses the breadth of the word in its spoken usage.
Born in the far north of Scotland in the early 1950s, not far from where the last wolf was killed in Britain and almost within sight of the ruins of a Pictish broch, I learned the word almost as soon as I was able to drink my free school milk unaided, for the weather in that area (one hundred miles north of Inverness) is almost always dreich.
As the saying goes in those parts, 'if you can see the hills it is about to rain and if you cannot see them it is raining already'.
The EL&U answer which quoted dreich was accurate in comment :
Your dictionaries, Martha, are inaccurate. The word dreich explicity implies humidity and dampness. It would never be used to describe dry conditions.
This agrees with my own usage (and the usage in the north of Scotland) to describe dark overshadowing clouds, persistent (though never copious) drizzle and a cold (though not frozen) wind.
It is such a suitable word for Scottish weather that I am surprised it has no foothold in other parts and I am convinced that it must have crossed the Atlantic - in the Mayflower or later - to lurk, perhaps little noticed, in some dreary location where it is whispered over mugs of steaming cocoa as the cold dampness knocks quietly at the door.
Is there any sign of it, in any shape or form, in AmE ?