But the surge is real, and it’s big. It could be enough to overcome Mr. Trump’s strength among white-working class voters in the swing states of Florida and Nevada. If it does, it will almost certainly win her the election.

In Florida, voters who indicated they were Hispanic on their voter registration form represent more than 15 percent of the early vote. In 2012, Hispanic voters were just 12 percent of the final electorate.

The numbers are striking in part because of the sheer magnitude of the early vote so far. Already, more than 6.4 million total voters have cast their ballots in the state — equal to 75 percent of the final turnout in 2012. In total, as many Hispanic voters have already cast ballots in Florida’s early voting period as cast ballots in all of 2012.

The Hispanic surge in Florida isn’t simply because Mrs. Clinton has drawn typically reliable Election Day voters to vote early instead: According to Daniel Smith of the University of Florida, fully 36 percent of the Hispanics who have voted so far did not vote in 2012.

It’s also striking because Hispanic voters are typically among the least likely to participate in early and absentee voting. If that pattern continues this year — suggesting a robust Hispanic turnout on Election Day — Mr. Trump is probably in serious trouble.