Should McCain Pray for Rain on Election Day?

Will John McCain's last hope for victory come from above? With his poll numbers wavering, the candidate may have to rely on a traditional Republican Election Day ally: Rain — particularly in key battleground states such as New Hampshire, Florida, Ohio, Virginia, and New Mexico.

A study conducted by political scientists last year verified the old American political adage that Republicans should pray for rain on Election Day. The researchers found that for every one inch increase in rain above its Election Day normal, the Republican presidential candidate received approximately an extra 2.5% of the vote.

"Our evidence supports the claim that bad weather lowers voter turnout," the authors write in the study, which was published in the Journal of Politics in 2007. "Bad weather (rain and snow) significantly decreases the level of voter turnout within a county … and poor weather conditions are positively related to Republican Party vote share in presidential elections."

The study was written by political scientists Brad T. Gomez of the University of Georgia, Thomas G. Hansford of the University of California, Merced, and George A. Krause of the University of Pittsburgh.

Reliable weather forecasts for Tuesday, Nov. 4 — Election Day — won't be available until this coming weekend.

"In political science, it's known that Democrats bear higher costs for voting than Republicans," says Krause. "And there is a greater cost to voting during inclement weather, which disproportionately affects people who are more likely to vote for Democrats," he adds.

Although waiting in line in bad weather or driving in potentially hazardous road conditions may not seem like major costs, "for many citizens, the imposition of an additional minor cost may make the difference between voting and abstaining," the authors write in the study.

The researchers analyzed the affects of precipitation and temperature on voter turnout in more than 3,000 U.S. counties for 14 U.S. presidential elections from 1948—2000, which they say is the most comprehensive test of the weather-turnout thesis ever done. There had been other studies before, according to Krause, but they were poorly done or not national in scope.

Whether in the form of rain or snow, precipitation was the major weather issue that kept voters away — the authors found that "cold temperatures do not significantly decrease voter turnout."

According to their research, three presidential Election Days from 1948 to 2000 had well above-average precipitation across the USA: 1972, 1992, and 2000, when rain or snow caused hundreds of thousands of voters to stay home.

While neither the 1972 nor the 1992 elections were close in the Electoral College count, the 2000 election certainly was. In the 2000 election, George Bush defeated Al Gore by a 271-266 count in the Electoral College, with Florida the closest of all, when just over 500 votes decided the state and then the entire election.

Although most of Florida was rain-free on Nov. 7, 2000, Hansford says that "meaningful amounts of rain fell in the Florida Panhandle — in Santa Rosa, Escambia, Okaloosa, Walton, and Holmes counties." This could have deterred some Democrats from getting to the polls that day.

"We are the first to find that something as simple as rainy weather in some of the Florida counties may have played a critical role in determining the outcome of a presidential election," write the authors. They conclude that "our results suggest that Democrats may need to increase significantly their mobilization efforts when rain is on the horizon."