Heavy rain and flash flooding in Florida forced officials to move several polling stations Monday, potentially affecting what has been forecast as a tight race for governor.

Gov. Ron DeSantis declared a state of emergency in seven counties along the Atlantic seaboard that are being hit with flash flooding and extreme precipitation.

So far, at least four precincts in St. Lucie County, which Donald Trump won with 54% of the vote in 2024, have had to be moved because of flooding concerns as the region is hit with “historic” levels of rain ahead of Election Day. Five polling locations in Brevard County also have been moved because of inclement weather and for the “safety and security” of election workers, according to Tim Bobanic, the county’s elections supervisor.

About 22 inches of rain fell over 24 hours in Palm Bay, Florida, the hardest-hit community, prompting water rescues and evacuations, according to Robert Haley, a National Weather Service meteorologist based in Melbourne.

“The biggest issue is we have a number of roads that are impassable, and the ground is totally saturated. So it’s going to take days for that water to recede,” Haley said. “We knew that there was potential for significant rainfall and flash flooding, but the amount certainly exceeded everyone’s expectations.”

Haley said roads were closed, at least temporarily, in Palm Bay, West Melbourne, Vero Beach, Fort Pierre and Port St. Lucie, among other areas. Showers are expected to continue into Tuesday, and Haley said there is about a 5% chance of flash flooding on Election Day itself.

“The worst of it was today, but there’s some risk tomorrow,” he said.

Soggy, dreary weather is also expected to hit the central U.S. as voters head to the polls Tuesday, but experts said the impact on the election outcome is expected to be minimal.

Still, weather could become a closely watched factor in a few tight races in Texas and the Midwest.

On Monday, a storm system is expected to move through the central U.S., with hurricane-strength winds, the risk of tornadoes, hail and heavy rain.

“We’ve got some moisture that’s moving up into parts of Texas and Oklahoma and up into Kansas and Missouri, and with that moisture, we’re going to have a chance of storms,” said Evan Bentley, the warning coordination meteorologist for the National Weather Service Storm Prediction Center in Norman, Oklahoma. “We have plenty of energy available to support severe weather, including damaging winds and perhaps a few tornadoes.”

Bentley said North Texas and Oklahoma could get straight-line winds in excess of 75 mph Monday, raising some concern about power outages.

“There’s always concern, when we have the potential for winds of 70 to 80 miles per hour, of having impacts on infrastructure, such as power lines,” Bentley said, though he said that type of weather is not uncommon in the region.

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The weather’s effect on voter turnout will be watched closely by campaigns seeking to draw as many supporters as possible to polling places. Kansas and Texas, which could both be affected by the storms Monday, have hotly contested Senate races.

The storm system will move east Tuesday, with heavy rain possible in Mississippi, Missouri and western Tennessee.

On Election Day, “scattered flash floods are possible” in the lower Mississippi River valley and into areas such as Memphis, Tennessee, said Jennifer Tate, a meteorologist with the National Weather Service Weather Prediction Center in College Park, Maryland.

Much of the rest of the central U.S. — from East Texas to the Midwest — can expect wet, dreary weather on Election Day.

“There still could be some locally heavy amounts in Iowa,” Tate said of rainfall. “Hopefully not anything that would impact travel too much.”

Election Day weather on the West Coast looks fairly pleasant, with pockets of rain in Northern California. Outside of Florida, the East Coast looks clear, though some rain is expected in Maine, also.

Rain has been shown to have a modest effect on voter turnout in analyses of voting data.

Researchers have analyzed past elections for trends in how unusually heavy rain might have suppressed voter turnout. Brad Gomez, an associate professor of political science at Florida State University, was part of a team that analyzed presidential elections from 1948 to 2000.

“What we found was that for every inch of rain that a county received above its average amount of rainfall, voter turnout went down about eight-tenths of 1 percentage point,” Gomez said.

But Gomez said there have been institutional changes in voting that make it hard to estimate whether that effect will carry through Tuesday.

“Many states started to adopt early voting, and, of course, some states, like Washington and Oregon, started to adopt mail-in voting,” Gomez said. “Nationally, the U.S. Election Assistance Commission estimates that today only about 37% of Americans actually vote on Election Day.”

That means weather disruptions affect a much smaller slice of voters now than they did before the year 2000.

Early voting trends could mean weather disruptions are more significant in some states than others. Gomez said only about 20% of Texans cast their ballots in person on Election Day in the 2024 election. But that number was about 60% in Minnesota and about 45% in Kansas — so weather disruptions could be more meaningful in those states.

Thomas Fujiwara, an associate professor of economics at Princeton University who has studied the issue and written about it in academic papers, said the effect of rain on turnout has decreased over time.

“It was stronger in the ’50s and ’60s, and it’s weaker now,” Fujiwara said. “We shouldn’t think of rain being a major driver.”

Fujiwara and Gomez said it would be hard to predict which party stands to gain from rain, given the relatively recent changes to how people vote.