I use Weather Underground weather history and data ap. Type in zip code, date you plan on visiting that area, and you will get average high and low temps for that region. Last year we left Minneapolis for southern Texas on December 21, and temps moderated south of St Louis, MO. From that point we didn't fear frozen water lines. Ironically, while in southern Alabama after the new year, we experienced mid 20's for lows for three nights in a row. We were already set-up so we were able to take necessary precautions.