The cold has been here for awhile now. But is the ice safe yet? It depends on what lake and where you are on the lake. Here is a guide put out by Minn DNR:
Four inches clear ice for travel on foot
Five inches clear ice for snowmobiles and ATVs
Eight to 12 inches for cars or small trucks
Twelve to 15 inches for medium size trucks
And thats good, clear, solid ice.