The people rejected God. After some period of time, God will restore the people of Israel to their original place. The latter rains symbolizes Israel's restoration, God's blessings and God's use of the Israel. All scriptures are from the King James' version Bible. Israel's believed that just as the seasonal rains came to revive the earth, God's favor would come to revive his people.
Early rain starts the seed off.
Latter heavy rain gave them growth. God supplies the rain. As the fruit matures so will the tares. But while men slept, his enemy came and sowed tares among the wheat , and went his way. Rewards of God's blessing on man's labors.