I read an anecdote in Reader's Digest, possibly urban-legendish, about this. Some notable person (listed by name in the anecdote) went to Paris in April because of this song. Later on he met the author of the song and told him that he had gone to Paris in April and had a miserable time due to rain and cold. The author said something like - Oh, I know that. I much prefer to go in May. But I had to put April in the song to make it scan.
[This message has been edited by WillTravel (edited Jan 28, 2004).]