A commentator said the plagues follow a pattern of representing Egyptian Gods. The three in this chapter are Livestock, an attack on the Anubis, Egyptian god with a cow head. Egyptian cattle got sick and died, Israelite’s were spared… despite his stubbornness, Pharaoh was worried enough to investigate.
Imhotep, the god of medicine was attacked with the plague of boils. Its noted that the magicians, who would have been thought to be in closest communication with that god, can’t stand straight before the King because of the burning skin pain.
Hail and lightning would have been the most frightening of all, because it was seen as symbolic of God’s wrath pouring down from heaven, and attacked a number of gods, notably the sky goddess Nut.
Free will and pre-destination are on delicate display here: After the livestock dies, Pharaoh hardens his heart. After the boils: God hardens Pharaoh’s heart. With the hailstones and fire: God speaks a complex message to Pharaoh. Through Moses he reminds Pharaoh that his judgement could have been more harsh, he could have obliterated him and his land.
When the hail comes, the Egyptians self select who it affects because those who believed the prophesy took measures to protect their livestock and crops. Pharaoh confesses he has sinned, but by the end has sinned again and reneged on his promise to let them go.
For the Israelites who had assimilated to the Egyptian Gods, this is all a powerful message, as it is to me!