Komentarz do Amosa 4:7

when there were yet three months before the harvest—Until the harvest. I.e, three months before the harvest.

The second warning is that "I will cause the rain to cease". And this especially during the three month harvest season when rain is most needed. Because if the rains ceased at the beginning of the year there would be no planting (due to the drought) and at least the seeds wouldn't be lost and they would still have food. But now, it will not be the case. The year will start with rain, in order to encourage planting and then Gd will stop the rain for three months during the harvest in order for the seed that you planted to be lost and not produce a harvest. And so that you don't assume it is a natural occurance, the ceasure of rain will take place in a wonderous wonder that it will affect city by city with one experiencing rain and another not. And not just that it will rain in one city and not another, even more so, it will rain on parts of a city and My curse will dry out your portion. (8)-until two-three cities will gather in one place, because Gd will provide water but not enough to satisfy. And I have no doubt that the places that will experience the rain are through the merit of the people living there or through their teshuva. Gd says about them, even though you were incuded in the warning and judged for famine and thirst and didn't return to Me. About this Isaiah says (Isaiah 9:18) "the nation will be a like a fiery knife" meaning that when the rain stops the sun will strike the land with eat and because of the trouble caused by the famine and drought, man will not help his fellow and in the end you will not return to Me, although My Hand is outstretched. This makes it clear that a second warning doesn't have the power of a first warning. And it answers the first question

field Heb. חֶלְקָה, a fielded plain, campagne in French.

shall receive rain Heb. תִמָּטֵר, shall be a place of rain. The master stated: Both of them are for a curse; this one will rot, and this one will wither. [from Taanith 6b]

and the field upon which no rain shall fall—That will not show itself rained upon.