Donald Trump, who leads recent polls, called on supporters to brave freezing temperatures for the GOP's first nominating contest on Monday.
[Donald Trump / Former U.S. President]
"You got to get out. You can't sit home. If you're sick as a dog, you say, 'Darling, I got to make it'. Even if you vote and then pass away, it's worth it, remember."
The icy weather in the Midwestern state has become a wild card in a contest seen as a tone-setter for votes yet to come.
It may help begin to seal Trump's bid to become the Republican nominee, and in turn face Democratic President Joe Biden in November's general election.
His top rivals, former UN ambassador Nikki Haley and Florida Governor Ron DeSantis, are banking on strong showings in Iowa to rattle Trump's dominance.
But the extreme cold could throw a wrench in their plans by suppressing turnout.
Iowa GOP Treasurer David Barker was optimistic voters would shrug off the frigid conditions.
[David Barker, Iowa GOP Treasurer]
"We've had blizzards before. We've had extreme weather on caucus night, and, you know, it certainly is going to be cold. No question about that. And we want people to be careful, but I think we'll see strong turnouts."
A Des Moines Register/NBC poll released Saturday found that Trump had the most supporters saying that they were very enthusiastic about his candidacy, suggesting they may not be deterred by a forecast for the coldest Iowa caucus night ever - minus 20 degrees Fahrenheit.
The poll showed Trump with 48% of the support, while DeSantis, who has staked his bid on a strong showing in Iowa, had slipped to third place with 16%.
Haley, who has capitalized on donors' disappointment with DeSantis' lackluster campaign, had jumped to second place with 20% of those polled.
