Difference from average temperature estimated by GFS model at 1 p.m. today (WeatherBell.com)

With the exception of the Canadian border region of the northern Plains, the entire contiguous U.S. is experiencing above to much above normal temperatures today.

The sprawling, unusually warm air mass was responsible for at least 482 daily high temperature records Monday compared to not a single record low temperature. The warmth concentrated from the Plains to the mid-Atlantic.

Record highs set or tied Monday (open circles are tied records, circles with x indicate records broken) (National Climatic Data Center)

Among the cities setting record highs? Des Moines (69), Chicago (70), Wichita (72), Milwaukee (65), Joplin (73), Oklahoma City (79), Tulsa (76), Roanoke (73), and Washington, D.C. (71).

Of the daily record highs, 34 of them were also record highs for the month of December. Madison, Wi’s high of 65 was a monthly record as was Muskegon, Mi’s high of 66. Kansas City’s high of 74 tied its monthly record.

Additional records have started to fall today and more are likely, particularly in the Northeast where some of the warmest weather with respect to normal is occurring - in some places over 20 degrees! Already, Syracuse and and Watertown New York have established new records, having surged into the mid-60s.

Upper level winds and the jet stream (black line drawn on top of area of fastest winds) (WeatherBell.com)

The cause of the warm spell has been a strong Pacific jet stream running west to east along the Canadian-U.S. border, keeping Arctic air locked up in Canada.