In 1873, a frog-fall smote Kansas City; ditto for Dubuque, Iowa, in 1882. What was puzzling in both of those cases was that there were no bodies of water nearby. Experts theorized the Kansas City event was due to a tornado elsewhere that had carried the frogs to the city. Scientists studying the Dubuque case similarly believed the frogs were sucked up by a powerful wind, then encapsulated into hail before being dumped onto the unsuspecting citizens of Dubuque. More recently, in 2005, thousands of frogs fell from the sky into a town in Serbia. This frog-dumping occurred during a powerful storm, which a Serbian climatologist said was the reason behind the event [source: The Library of Congress].
While these explanations are the same as those for the fish-falls previously discussed, there might be additional reasons for frog rains. One is that the frogs aren't falling from the sky after all. Some people get so excited at the possibility, that they extrapolate the occurrence from a common one. It's possible that a major storm can drive frogs from their normal habitat. So if you look outside during a heavy storm and suddenly see frogs hopping around everywhere, you might think it was raining frogs, when actually the frogs hopped to your yard on their own.