This January was the fourth-warmest January on record for the continuous United States, according to the National Oceanic and Atmospheric Administration (NOAA).

According to NOAA data, Illinois temperatures ranked above normal during January 2012.

During 15 days in January 2012, temperatures in Romeoville hit the 40s and 50s, exceeding the average January high of 31 degrees.

"It's warmer this year mainly because of the jet stream pattern," said AccuWeather.com Senior Meteorologist Michael Pigott. "Generally, for the most part of the winter, it has been on a west-to-east pattern. Meteorologists refer to this as a 'zonal flow.' Essentially, we've seen a lot of storms moving from west to east, and not a lot traveling northward or southward. So, anything in the Arctic is staying up there, and anything in the U.S. is staying put as well. If you have north-to-south undulations in the jet stream, you do get warmer air heading northward to the poles, and colder air comes down toward the U.S. from the Arctic."

While temperatures aren’t expected to be as warm as they were in January, Romeoville-area residents may see the warm trend continue through February and March.

"It looks like the pattern will be similar for most of the country, but not to the same extent," said AccuWeather.com Expert Senior Meteorologist Jack Boston. "We are getting in a pattern where we're more susceptible to cold air masses coming down. However, that doesn't mean they're going to stay. They're still going to be progressive. That means cooler temperatures will come in for only a few days, then disappear again."