The inaugural boat parade at the Paris Olympics opening ceremony is under threat from an unwelcome competitor — rain. Paris woke up to rain today, and people are keeping their umbrellas handy. Meteo France, the French weather service, is predicting it will stay overcast all afternoon, and it's not ruling out rain during the opening ceremony.This is the first time an Olympics opening ceremony hasn't been in a stadium.The ceremony goes on rain or shine. Roughly 300,000 people have ticketed spots on the Seine's upper banks. Another 300,000 are expected to gather near the river to catch some Olympic spirit.