The mercury was fighting to hit 7 degrees as investors began pitching their tents near the Gwinnett County Courthouse just outside Atlanta. It's "Super Tuesday," and that means nearly 3,000 foreclosed properties will be set for auction across the greater Atlanta area, no matter what the temperature outside.
"Only the real die-hards are out here in 7 degree weather," said Rick Sharga, executive vice president at Auction.com, which conducts the bidding for the bulk of the properties. "It just shows you that there is still a lot of active interest in this trade. It is far from over."
Not all the properties will be sold; Sharga estimates about 1,800 will sell, but at an average sale price of $100,000. That's $180 million in one day in one housing market.
"I don't think there is any chance that this is going to be over for at least another two years," said Simon Frost, CFO of Key Property Services, which will buy about 100 properties at multiple auctions on Tuesday. "We have about 60 people on the ground today."
Key buys the homes, rehabilitates them, and sells them to other investors as turn-key rentals. Some of the individual investors shivering in the cold will also buy the homes to flip, but others are in for the long haul.
(Read more: US apartment vacancy rate drop, rents rise)
Kirby Hamilton | E+ | Getty Images
Representatives of Blackstone's Invitation Homes huddled under blankets and sat at a long table with packets of handwarmers. Blackstone is the largest player in the so-called REO-to-rental market (REO means real estate owned or foreclosed). Those at the table are directing a veritable army of bidders, working their way through the crowd from auction to auction. Blackstone's representatives sternly refused to talk, but it is clear they will be spending millions of the hedge fund's dollars just Tuesday.
"They're robots," said an independent contractor working for another investor. "And there's nothing wrong with that. It's a job. They do what they're told." He, too, did not want to be identified.
Home prices nationwide rose 11.8 percent in November, according to a report released Tuesday from CoreLogic. That is the 21st-straight month of annual price appreciation. Those gains have been pushed primarily by investors on the low end of the distressed market, but they have priced themselves out of some markets, so they are now on the move.
"As the foreclosure discount has gone away in some of the warmer states, investors are looking for markets where they have properties that fit their sweet spot of somewhere between $85 and $150,000," said Sharga. "That's the range where they can afford to buy a property and rent it out and get the kind of returns they need to deliver to their investors."
(Read more: US dominates list for foreign real estate investors)
Phoenix, Las Vegas and much of California no longer offer the best returns. In fact, they are not even in the top 10. Looking at costs of acquisition, rehabilitation, rental rates and maintenance, CoreLogic found Chicago, Tampa, Orlando, Atlanta and Indianapolis now offer the best investor returns for investors in single-family rentals.
(Read more: The best place to invest in real estate is …)
"Atlanta is still one of the very early movers in home price appreciation and in distressed asset acquisition, so we think there are a lot of states, especially judicial states that will start releasing stock over the next few years and we want to be there when they do," said Frost. He expects to start moving into Maryland and New Jersey in the near future.
As for investors who started early in the so-called "sand states," some are beginning to sell a few of their properties to other smaller investors, but they are staying in the trade themselves by lending to those same investors. Blackstone recently announced a new program to finance small investors buying multiple rental properties.
(Read more: Housing recovery sparks pickup in home seizures)
It may be incestuous, but really it is just the next step in the trade. Rental demand is expected to remain strong for the next few years, as household formation is still weak; most households being formed today are rental households anyway. The nation's home ownership rate may continue to fall in 2014, as mortgage credit remains tight and wage growth lackluster at best.
By midday Tuesday, the sun was warming the sidewalk outside the courthouse, and the temperature was up in the teens. Those who started early were still bidding, clutching steaming thermoses of coffee. One even noted that the auctioneers were pushing properties faster than usual, closing the bidding quickly, in order to get through it all and get out of the cold. That means better deals, he added with a warm smile.
—By CNBC's Diana Olick. Follow her on Twitter @Diana_Olick.