Charles Ellicott Commentary Leviticus 26:4

"then I will give your rains in their season, and the land shall yield its increase, and the trees of the field shall yield their fruit." — Leviticus 26:4 (ASV)

Then I will give you rain in due season. —Better, then I will give you your rains in due season, that is, the former and latter rains (Deuteronomy 11:14). In Palestine the proper season for the early rain is from about the middle of October until December, thus preparing the ground for receiving the seed, while that of the latter or vernal rain is in the months of March and April, just before the harvest. Thus, also, in the covenant which God is to make with His people, a similar promise is made, I will cause the showers to come down in his season; there shall be showers of blessing (Ezekiel 34:26).