Today (Tue Dec 8) Frontier has a travel waiver for Milwaukee and nowhere else. Southwest and United (moreso) have much broader waivers. There is/was significant weather in DSM, OMA, MSP, MCI and some snow in Chicago/Denver. In my opinion it is pretty poor customer service to force people with somewhat flexible plans to either drive through bad and dangerous road conditions and then sit at airports through delays or alternately incur a change fee plus fare difference.

Just saying.