Exo 9:17 As yet exaltest thou thyself against my people, that thou wilt not let them go?Exo 9:18 Behold, to morrow about this time I will cause it to rain a very grievous hail, such as hath not been in Egypt since the foundation thereof even until now.
Exo 9:19 Send therefore now, and gather thy cattle, and all that thou hast in the field;
for upon every man and beast which shall be found in the field, and shall not be brought home, the hail shall come down upon them, and they shall die.
Living in Florida I see a lot of hail during the rainy and hurricane season. So I can relate to hail. Now think back to Sodom and Gomorrah. I cannot even think of the effect of this on the land and people of Egypt. Think of it like this: It is now raining down incendiary armor piercing rounds. Here is the account from the Book of Genesis :
Gen 19:23 The sun was risen upon the earth when Lot entered into Zoar.
Gen 19:24 Then the LORD rained upon Sodom and upon Gomorrah brimstone and fire
from the LORD out of heaven;
Gen 19:25 And he overthrew those cities, and all the plain, and all the inhabitants of the cities, and that which grew upon the ground.
At this time in Egypt, the capital city was Memphis, not Cairo. Memphis hardly gets rain or heavy storms. So before the hail started you had lightning and thunder. This had to have unhinging effects on the Egyptians. Now Pharaoh, with a hardened heart and a frightened people, would turn to nut, the goddess of the sky. And shu (who's name means void) was the god over cooling wind and breezes. The god over thunder and lightning was seth. Pharaoh was also called by the name of seti. Seti is also another name for baal. This is part of god on earth worship. There is always more to a great stronghold than walls.