How do I know? For starters, it is only 4:40 PM and it's pitch dark. Sunset is at 4:18 PM today, and the sun doesn't rise until 7:48 AM tomorrow! And our days will keep getting shorter for at least another week.....
Many mornings are very foggy. Sometimes the fog burns off, and the temperature drops. Today's fog stuck around all day long.
All of the leaves are pretty much gone; the big leaf maples and the ginkos are among the first to fall.
Rabbits are seldom seen, but there are lots more places to hide.
Last minute road projects are everywhere. This mess is just around the corner; they are doing something to the cell towner that has required tearing up these folks' frontyard.