I also have withholden the rain from you; your vanities could not, and because ye did so greatly sin against me I would not, give you rain; I forbade the clouds from above, and they, thus prohibited, did withhold their rain, as I threatened, Deuteronomy 28:23,24. When there were yet three months to the harvest; at a season when your country most usually had, and as then it ever did most need, rain: see Joel 2:23. Three months drought then, as it was unusual in the course of nature, so it was an extraordinary curse and punishment on them. That you might see my hand in it and be instructed, I gave rain to one city, and withheld rain from the next neighbour city; nay, one part of a field, the same field, was watered and flourished, another part dry and withered. All this to convince and turn you.
Related Commentaries of Amos 4:7
Amos 4:7
7 And also I have withholden the rain from you, when there were yet three months to the harvest: and I caused it to rain upon one city, and caused it not to rain upon another city: one piece was rained upon, and the piece whereupon it rained not withered.