Why did Elijah pray for no rain for three years and did it change Ahab and Jezebel?
Elijah interceded against Israel because they had killed the prophets, destroyed the altars, and sought his life, so he caused a three-year drought as judgment. It did not change Ahab and Jezebel; despite the utter drought, they would not change their wicked, Baal-promoting ways.
Les explains that Elijah's setting was the reign of King Ahab and Jezebel in the northern kingdom. Ahab was an ungodly, wicked king, and Jezebel was the wicked queen; together they promoted the worship of Baal and idol worship, and the Israelites were falling for it. Elijah had even gone so far as to cause no rain for three years, producing an utter drought. Yet Ahab and Jezebel still would not change their ways. By the end of that drought, northern Israel was burned up from lack of water. Elijah then gathered all the Israelites and the prophets of Baal together on Mount Carmel for the confrontation.
And Elijah the Tishbite, who was of the inhabitants of Gilead, said unto Ahab, As the LORD God of Israel liveth, before whom I stand, there shall not be dew nor rain these years, but according to my word.
Elias was a man subject to like passions as we are, and he prayed earnestly that it might not rain: and it rained not on the earth by the space of three years and six months.