We have lots of "patchies" in our weather forecasts. Patchy fog, patchy rain, patchy drizzle, even patchy frost. It's the non-committal way of saying that, in spite of the fact that we have the world's finest computers and the most talented modellers, we can't tell you whether you'll get these types of weather or not where you live. We also have "chance of...", "scattered showers," "sunny spells/periods/intervals/breaks" and "possibly with the odd rumble of thunder."

One dictionary I just consulted referred to ""wrap up" as a phrase verb. That makes a qualifying word following it an adverb, I guess. It may be informal, but "wrap up warm" is clear and effective in its message!