IRON MOUNTAIN — Temperatures in the region have yet to get below zero this winter but that will soon change, forecasters say.

Arctic air will invade this weekend in the wake of a storm expected to deliver 7 or more inches of snow in the central Upper Peninsula.

The heaviest and wettest snow fell Friday. Lake effect snow is expected Saturday when winds could gust at up to 40 mph.

Snow totals of up to 18 inches are possible in the Chicago area, said AccuWeather meteorologist Bernie Rayno.

“As the storm turns the corner and heads northeastward over the southern Plains, the strengthening process will begin with a vengeance as Arctic air is injected,” Rayno said. Blizzard conditions may expand to at least six states in the Midwest, he said.

Temperatures are expected to plunge to near zero Saturday night and stay in the single digits or lower through Tuesday, according to the NWS. Predicted lows are below zero.

Wednesday should be partly sunny.

The long-range forecast, meanwhile, continues to favor a milder winter. The Climate Prediction Center indicates a 45% chance of above-normal temperatures and below-normal precipitation through March in the Upper Peninsula and northern Wisconsin.

There is just a 20% chance of below-normal temperatures and above-normal precipitation as El Nino conditions persist into spring. El Nino, a natural climate cycle that temporarily warms parts of the ocean and affects weather patterns around the world, is typically associated with milder winters in much of the northern U.S.

The U.S. Drought Monitor showed severe drought in Florence County, Wis., as well as the western half of Gogebic County in the U.P. There was moderate drought in northern Marinette County and Forest County in Wisconsin, along with the U.P.’s Houghton County and eastern Gogebic. Elsewhere in the U.P. conditions were abnormally dry.