I recently saw a television show that talked about a rainstorm in Kansas City, Mo. That took place in the late 1800’s. This rainstorm for a brief time also included frogs falling from the sky. Way too many of them for them to have been nesting in the trees. It was such an unusual event that for years they thought the observers must have been mistaken. Later someone figured out that a waterspout could have been the explanation. A sort of water tornado picked up the frogs from a semi-local body of water and dropped them off as the waterspout was running out of energy. This explanation would have been fine for that event. They went one step further and said that the waterspout explained the plague of frogs, but would it?
The Biblical rain of frogs was not a surprise to Moses, God told Moses, and Moses told the Pharoh, and then Aaron was told to stretch out his staff over the local bodies of water before the plague of frogs came into being.  Then when the Pharoh told Moses to stop the frogs, Moses told him to wait till the next day. On the next day, all the frogs died, and everything stank.  The frogs in Kanas City left of their own free will. So the plague of frogs looked completely different than the surprise storm in Kansas City.
You have the other 9 plagues to consider, and how many of the plagues did not affect the Jews who wanted freedom from slavery.  If you want a natural explanation for the frogs in the Bible you have to explain away all ten plagues, and the reason why the Pharoh let the Jews go free.

When I was reading up on the ten plagues of the Bible, I remembered a story that I heard years ago.

A boy was sitting on a park bench with one hand resting on an open Bible. He was loudly exclaiming his praise to God. “Hallelujah! Hallelujah! God is great!” he yelled without worrying whether anyone heard him or not.

Shortly after, along came a man who had recently completed some studies at a local university. Feeling very enlightened in the ways of truth and very eager to show this enlightenment, he asked the boy about the source of his joy.

“Hey” asked the boy in return with a bright laugh, “Don’t you have any idea what God is able to do? I just read that God opened up the waves of the Red Sea and led the whole nation of Israel right through the middle.”

The enlightened man laughed lightly, sat down next to the boy and began to try to open his eyes to the “realities” of the miracles of the Bible. “That can all be very easily explained. Modern scholarship has shown that the Red Sea in that area was only 10-inches deep at that time. It was no problem for the Israelites to wade across.”

The boy was stumped. His eyes wandered from the man back to the Bible laying open in his lap. The man, content that he had enlightened a poor, naive young person to the finer points of scientific insight, turned to go. Scarcely had he taken two steps when the boy began to rejoice and praise louder than before. The man turned to ask the reason for this resumed jubilation.

“Wow!” exclaimed the boy happily, “God is greater than I thought! Not only did He lead the whole nation of Israel through the Red Sea, He topped it off by drowning the whole Egyptian army in 10 inches of water!”

You see context is important! You can explain away almost everything if you break it down into bits, but explaining away the whole narrative is extremely difficult, especially if the narrative is based on truth!

You may also be interested in reading Miracles, by C.S. Lewis