Rain can tilt elections. Between 1948 and 2000, for every inch of rain on Election Day in a given county, there was an average 0.8 percent decline in turnout.
Computer modeling has indicated that if it had rained in Illinois in 1960, Nixon would have beaten Kennedy—and if it had been sunny in Florida in 2000, Gore would have beaten Bush.
From Discover Magazine
*yoinked from useless_facts*