Honduras I believe is the only place in the world where it rains fish once a year. It happens in the department of Yoro sometime between May and July. There is no specific day, but if you want to have a truly unusual experience in a trip this would be it, but you would need to plan an extended vacation since there is not a set day.
There is no credible explination for this phenomenon through science, but it really does happen. Tradition here says that Father Jose Manuel Subarina came to Honduras and upon finding so many desperately poor people he prayed for 3 days and 3 nights and upon that it rained fish providing a blessing for the people that has continued on every year.
What is interesting is the phenomenon includes fish that are not from that area and are fresh water fish. It does occur only during a very strong thunderstorm that lasts at least 3 hours so it needs to be a torrential rain storm before you will get the raining of fish. It also usually occurs around 4 or 5 in the afternoon. Something even more interesting is that none of the fish that have fallen from the sky have been able to be kept alive, they all die within a few hours regardless of what is done, so it seems they are sent to be eaten and not grown. The fish rain starts from a very black rain cloud that rises up over the mountaintop and always originates from the same direction, it is most likely that it will occur sometime between June and July but evidently has occurred in May as well. What is interesting is how this always occurs year after year one time a year.
So grab your basket and come to Yoro during this season if you want to experience what it is like to have it rain fish.
Here is a Youtube video of the area where it occurs