Warmer than normal temperatures are keeping skiers away from the slopes in the Midwest during the holiday season, normally one of the busiest few weeks of the year.

According to the National Weather Service, the average high temperature in the Chicago area during December is around 35 degrees. So far this year, the average high has been closer to 42 degrees. In Milwaukee, this month’s average high temperature is around 40 degrees, compared to an average of around 33 degrees. The same is true in the Grand Rapids, MI area.

“Do I think that it’s going to impact the final numbers? If we don’t get snow or some really good temperatures soon, yeah,” said Stephanie FitzSimons, marketing manager for the west suburban Bartlett Park District, which owns ands operates Villa Olivia and its ski slopes.

FitzSimons said normally they’d make snow to coat the slopes, but she said the warmer temperatures make it pointless. As a result, the park’s been closed more than open since its season began in mid December.

A spokesperson from Grand Geneva Resort in Lake Geneva, Wis. said the resort is seeing about half the ski traffic they normally expect at the end of December. In Otsego, Mich., Bittersweet Ski, which sees about 100,000 people annually, has cut down the number of runs it’s operating because of the warmer temperatures.

Spokesman Tom Smitchols said the week between Christmas and New Years is usually one of the busiest, but that’s not been true this year. He echoed the sentiment that the unseasonably high temperatures might bring down annual income.

“We lose a major weekend — or week — that’s going to affect our total number of skiers for the year,” said Smitchols.

The National Weather Service is predicting the high temperatures will stick around at least until after the New Year.