BOSTON — Fluffy, granular snow blanketed New England on Friday morning, accumulating up to four inches in some places and leaving roads slick and slushy, five days ahead of an election whose outcome is expected to hinge on voter turnout.
Both rain and snow are shown to depress turnout, but Friday’s snow is expected to melt over the weekend, with Election Day on Tuesday forecast as chilly but dry.
Early voting and campaigning has already been disrupted this week by the extremities of the weather: powerful Santa Ana winds fueled wildfires in Southern California and Hurricane Zeta knocked out electricity at some polling stations as it carved a path through the South.
But like New England, much of the country can expect clear skies on Election Day, with seasonably cool conditions in the Northeast and Upper Midwest, mild weather stretching through the South and over the Rockies and warm weather in store for Southern California. The Pacific Northwest, however, may be in for showers.
“Republicans should pray for rain” is an adage in American politics, suggesting that marginalized voters who tend to support Democrats are the most likely to be deterred by weather, and a 2007 analysis of 14 presidential elections published in the Journal of Politics seemed to bear it out.
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Historically, every inch of rain reduced the turnout by around 1 percent, whereas every inch of snow reduced it by 0.5 percent, the authors found. In both cases, Republicans benefited.
“The strong positive effect of rain is robust in the face of more comprehensive and complex model specifications,” the report said.
More recent analysis, however, suggests that the effect of weather is decreasing, perhaps because more voters are casting their vote before Election Day.
“It could also be that, over time, people just got better at dealing with rain,” said Thomas Fujiwara, an associate professor of economics at Princeton University. “Maybe weather forecasting got a little better. In the 1950s, you could be surprised when it snowed.”
In midterm elections, when turnout tends to be limited to more motivated voters, rain has no observable effect. And in any case, a weather event would have to be “fairly sizable” to shift turnout in any measurable way, he said.
“Most of the uncertainty is not related to nature, it’s man-made things,” he said. “I’m more curious about what the judges and election officials will do than what the voters will do.”
October snow is not unusual in the Northeast, but it rarely accumulates to a measurable depth. Nine years ago, a blockbuster Oct. 29 storm deposited 20 inches, an event that is remembered as “Snowtober.”
On Friday, a cold front moving south from Canada encountered the moist remnants of Hurricane Zeta, turning a heavy rain into powdery, dry snow, said Rodney Chai, a meteorologist with the National Weather Service near Boston.
Temperatures are expected to rise to around 50 degrees on Sunday, and any remaining snow will melt.
Friday’s snow will last until then in part because it is fluffy, Mr. Chai said.
“When the snow has a ‘fluff factor,’ because of air spaces in between the flakes, it can accumulate more effectively,” he said. With higher temperatures, “the dendrites lose their shape a little, they become rounder.”
And the predictions for Tuesday? Chilly and clear in New England.
“I cannot comment about implications on turnout, but I can tell you that the weather is going to be cold and dry,” Mr. Chai said. “We provide the public with weather information. We don’t speculate on the implications.”