The contrast between the two air masses was stark, and by the morning of October 29 the cold front was about halfway through Texas. At 6 am CST, the temperature in the western Texas city of Amarillo had dropped to 22 degrees with a strong northerly breeze. Farther east in Texas, the temperature was 64 in Dallas – a 42-degree temperature difference over about . In the northern United States, morning lows were much colder. Temperatures were in the single digits across Montana and Wyoming and in the teens in North Dakota and South Dakota.