Good news for Democrats: It's nice out today.
According to serious academic research, bad weather means bigger Republican gains. And, on balance, it's a nice day in the U.S. today, with a low-pressure system hovering over noncompetitive races in Louisiana and Arkansas, where Republicans are expected to win big anyway.
Here's a map of national weather today, from Weather.com:
Typically, Republicans gain a few percentage points from rain, according to a 2007 study by Brad Gomez of the University of Georgia, Thomas Haverford of the University of California, Merced, and George Krause of the University of Pittsburgh, who found that:
...when compared to normal conditions, rain significantly reduces voter participation by a rate of just less than 1% per inch, while an inch of snowfall decreases turnout by almost .5%. Poor weather is also shown to benefit the Republican party's vote share.
More precisely, for every one-inch increase in rain above its election day normal, the Republican presidential candidate received approxi- mately an extra 2.5% of the vote. For every one-inch increase in snow above normal, the Republican candi- date's vote share increases by approximately .6%.
The most obvious effect of bad weather, however, is suppressed turnout. It stands to reason that bad weather wouldn't always benefit one party, but rather the party with the most die-hard supporters or the candidate with the best get-out-the-vote operation.
Good weather, it seems, could benefit Republicans today if Democrats really do have a better turnout operation, as it's been suggested in 2010. Then again, if Tea Partiers count as the most die-hard voters this year, a rainy Election Day could very well have meant larger-than-expected gains for the GOP.
Using weather to predict elections is something of a parlor game, but perhaps Democrats have dodged a bullet.