Voters line up outside Bright Family and Youth Center in the Columbia Heights neighborhood in Washington on Nov. 6. (Pablo Martinez Monsivais/AP)

Forecasts called for brighter weather by late afternoon, but that prediction did not keep early-morning voters warm on Tuesday. A broad area of low pressure with a flanking cold front made democracy a little more taxing in the Mid-Atlantic, or at least a little more wet.

Though rain tends to keep people indoors, Tuesday’s weather was unlikely to significantly decrease voter turnout. Not only were the clouds predicted to part, but early reports from Washington-area polls suggested that the turnout numbers were high for a midterm election.

Susan Campbell, 65, waited for nearly a half-hour in the rain to vote in Washington’s Cleveland Park neighborhood. What was expected to be light showers turned into sporadic downpours as polls opened in the District. Campbell stood in line outside with her son and husband.

“It’s our responsibility. It’s our privilege,” she said. “How can I possibly complain if I didn’t vote?”

While the cold front inched east, south winds pushed humid air into the Southeast and Mid-Atlantic. The air was so humid in North Carolina that paper ballots were too damp to be fed through the vote-counting devices, according to the state’s Board of Elections, like wrinkled dollar bills rejected from the vending machine.

“When ballots cannot be read by the tabulators, they are stored securely in ‘emergency bins’ and will be tabulated as soon as possible,” the board said in a statement. “All ballots will be counted,” it added.

Near Richmond, 76 people were in line at the Gayton branch of the Henrico County Public Library when the polls opened at 6 a.m. By 10 a.m., with the weather waffling between fog, rain and mist, 651 voters had cast ballots and 90 more were lined up during what should have been a lull between the morning and lunchtime rush hours. The wait was 20 to 30 minutes, and the library parking lot was so packed that some voters opted to park on neighborhood streets on the other side of a busy four-lane road.

In Northern Virginia, Jeff Stubin, an official at the Sycolin Creek Elementary School polling place in Loudoun County, said there were 150 voters per hour in the first three hours. When asked how that compared with prior years, he thought for a second and said: “That’s almost presidential numbers.”

A 2007 study concluded that foul weather — mainly rain and snow — decreased voter turnout and benefited Republicans. For every inch of rain, turnout declined by just under 1 percent, the study found. The bad weather dissuaded Democrats the most. Results from a survey conducted by the Weather Channel before the 2012 election confirmed that finding.

However, 37 states and the District of Columbia have implemented early voting in 2018, and millions more voters have taken advantage of that convenience than in the 2014 midterm elections. According to Michael McDonald, a political scientist at the University of Florida who also runs the United States Election Project, more than 38 million votes had been cast before Tuesday, compared with 20.5 million in 2014.

The other reason that weather probably won’t affect turnout: It’s not going to rain all day.

In Washington, the cold front is forecast to pass by 4 p.m., after the potential for a brief deluge and scattered thunderstorms. That would leave at least three hours of relatively dry weather in which to vote.

That should also be the case as far north as New Jersey and Upstate New York. Evening voting could be wet in New England, where the front isn’t expected to pass until 9 or 10 p.m.

People line up outside Murch Elementary School in Washington on Nov. 6, 2018, to cast their ballots. (Liz Weber/The Washington Post)

Democratic Party volunteers take cover from the rain as they wait to speak to voters outside a polling station in Lorton, Va., on Nov. 6. (Andrew Caballero-Reynolds/AFP/Getty Images)

Marisa Iati and Laura Vozzella contributed to this report.