Seattle's nights warmer than many cities' highs

I've received plenty of e-mails from those who have relatives shivering in the massive arctic outbreak that has struck the eastern 2/3rds of the nation, and some of the statistics have been staggering.
In fact, on Thursday, Seattle had a high of 49 and a low of 39. But there were dozens of cities in typically warmer climates that were colder for a high temperature than Seattle had for its nighttime low.
Some of the biggies:
Tucson: 38
Houston: 32
Dallas: 23
New Orleans: 39 (tie)
Oklahoma City: 20
Atlanta: 39 (tie)
El Paso: 18
Albuquerque: 18
San Antonio: 28
Here is the full size of the map:

Need more cold stats? Our super weather intern Aaron Hill found all these for Thursday:
All-Time Records
Record Old
Fort Huachua, AZ 6.8
Davis-Monthan AFB, AZ 17.8
Pine Springs, TX -2.8
Grants, NM -18.8
Holloman AFB, NM -15.6
Monthly Records
Tucson, AZ 19.0 19.9
Imperial, CA 24.1 26.1
Clovis, NM -4.1 1.0
Douglas Bisbee, AZ 9.0 10.4
El Centro, CA 21.0 25.0
Las Cruces, NM 1.4 8.4
El Paso Airport, TX 1.9 8.1
Deming, NM 1.9 11.8
Daily Records
Tulsa, OK -2.8 0.0
Joplin, MO -7.0 -5.1
Midland, TX 9.0 12.9
Santa Fe, NM -8.9 0.0
Aspen, CO -19.9 -0.9
Just Really Cold
Alamosa, CO -23.9
Gunnison CO -23.7
Amarillo TX -1.9