The gods could be smiling on Barack Obama come Nov. 4.

Weather forecasters AccuWeather.com predict sunny skies across much of the country on Election Day, and good weather has historically helped Democrats at the polls.

A 2005 study found that lousy weather typically helps Republicans, as less-dedicated voters who typically favor Democrats tend to stay home rather than wait in line in the rain and snow.

To be precise, turnout drops by just under 1 percent for every inch of rain, or one-half percent for every quarter inch of snow, according to University of Pittsburgh professor George Krause, who co-authored the study.

So what’s the outlook for Tuesday? Unseasonably dry and warm across most of the Lower 48 states, according to AccuWeather.

Showers are forecast for the Pacific Northwest and Upper Midwest, where polls show Obama leading Republican rival John McCain by substantial margins.

But the widespread popularity of early voting could lessen any weather-related impact on Tuesday’s vote, Krause told Accuweather.

A boost for McCain? Maybe not. A Pew Research Center study released earlier this week found that Obama leads McCain by 19 percentage points among those who have already cast their ballots.

Click here for more Reuters 2008 campaign coverage. 

- Photo credits: Reuters/Jason Reed (Obama on a warm October 31 in Iowa); Brian Snyder (McCain speaks at a sunny Ohio rally)