The forecast in some states on Election Day is…rain. The all-important battleground states of Michigan and Wisconsin are both expected to be pelted with warm-weather thunderstorms Tuesday, one of those unpredictable Election Day variables that could dampen turnout,

CNN’s Meteorologist Derek Van Dam reports on Election Day weather that will impact key battleground states, urging voters to prepare for heavy rainfall and potential flash floods as they head to the polls.

Tens of millions of Americans are flocking to polling locations across the nation on Election Day, and in some cases, the weather will be a factor for those waiting in lines outside. The nation is divided by a sprawling south to north cold front.