Below is the footnote in the NET for "north wind":
sn One difficulty here is that it is the west wind that brings rain to Israel (e.g., 1 Kgs 18:41-44). C. H. Toy suggests that the expression is general, referring to a northwest wind—unless it is an error (Proverbs [ICC], 468). J. P. M. van der Ploeg suggests that the saying originated outside the land, perhaps in Egypt (“Prov 25:23, ” VT 3 : 189-92). But this would imply it was current in a place where it made no sense. R. N. Whybray suggests that the solution lies with the verb “brings forth” (תְּחוֹלֵל, tkholel); he suggests redefining it to mean “repels, holds back” (cf. KJV “driveth away”). Thus, the point would be that the north wind holds back the rain just as an angry look holds back slander (Proverbs [CBC], 149). But the support for this definition is not convincing. Seeing this as a general reference to northerly winds is the preferred solution.
The NAC-Proverbs, Ecclesiastes, Song of Songs commentary (Duane A. Garrett, p. 209) regarding Pr 25:23 has this:
This little proverb is extraordinarily beset with problems. The first is that the north wind does not bring rain in Israel; the second is that the phrase "brings rain" is literally "has the birth pangs of rain" (which is subject to various interpretations), 15 and the third is that the Hebrew does not make clear whether the "sly tongue brings angry looks" or whether it is the other way around. Yet one could interpret it, with paraphrase, as follows: "As a cold wind gives birth to rains, so cold looks give birth to a storm of slander." The point of the north wind is not meteorological accuracy for Israel. The proverb may have arisen in Egypt, where the rains could be from the north and are as unwelcome as they are usually welcomed in Israel. Rather, the north wind is cold, and it corresponds to cold looks on the faces of people in a hostile environment. The downpour of water in the rains corresponds to a flood of secret defamation that occurs where people do not communicate with one another.
Footnote 15: This phrase could be taken to mean that the north wind is frightful to rain and thus inhibits it, but I consider this implausible.