Temperatures late this evening are tumbling across the plains. Readings below zero with wind chills as low as -35° were reported in North Dakota at 11pm. Aberdeen had a temperature of only 7° with a wind chill of -16°. This cold wave is expected to make an appearance in NW Iowa before sunrise and sweep across the state on Sunday. The temperature drops will be severe on Sunday with 15-20° drops in a span of as little as 4 hours.