Every Fall, I try to pay attention to the first time it starts getting rather cold out. I judge that by asking myself what is the date when my car FIRST tells me the temperature has dropped to 39.
When the temperature drops to 39, my car will ding at me, flash the temperature on my dashboard and put a snowflake next to the number. Well, it happened last night on my way home from work for the first time this season. So this year's answer is October 25th.
Here's to hoping we don't have to deal with temperatures much below that 39 too often this season.