In Palestine there is commonly hardly any rain from the early showers of spring to October. Hence, “rain in harvest” became sometimes (see the marginal reference) a supernatural sign, sometimes, as here, a proverb for whatever was strange and incongruous.
Related Commentaries of Proverbs 26:1
Proverbs 26:1
1 As snow in summer, and as rain in harvest, so honour is not seemly for a fool.