How does the weather seem to know the actual date ? 
I mean, down here Labour day is seen as the last day of summer, it’s usually blisteringly hot then a day later the A/C is off untill mid morning and I am wearing a light jacket first thing, we did have a couple of extremely hot days this week but I put that down to the Indian summer thing, when it gets to October here it changes again almost the day after Halloween 
… Nine times out of ten it snows the very next day
Our swimming pool is crystal clear, better than it’s been all year and so cold it will freeze your nuts off.