This week has been very comfortable for many in the US. An Indian Summer (temperatures above 70 degrees with clear skies following the first frost) has affected much of the eastern 2/3 of the lower-48.
It will continue to migrate eastward as the cold in the Pacific Northwest begins to sweep across the Plains and into the eastern US. The next five days will see temperatures below normal in western Canada and much of the central and western US.
The following 5 days see the cold air move southeast.
So, if you have work to do outdoors before Winter sets in, this would be a good week to do it. It’s not that temperatures will never be mild again this year, but I doubt we’ll see five straight days in the 70s across the northern Plains, Great Lakes, and Northeast between now and Spring 2013.