Extreme windchill values of minus 40 are expected to develop overnight as another shot of cold arctic air invades southern Manitoba from the north. With the mercury expected to dip below the minus 30 degree mark by morning and light northwesterly winds of 10 to 15 km/h, windchill values will be in the minus 35 to minus 40 range tonight and dip below minus 40 early Saturday. Conditions may improve slightly during the day Saturday but extreme windchills are likely Saturday night and early Sunday morning, as well."