Very early sign of autumn?

A few evenings ago, as I was going out to buy some stuff, I saw these leaves in an alley of bushes. They had already changed colours. I was very surprised. It has been a fairly cool summer so far, with a week of heatwave at the most, but we're only in July and autumn is still a long way down the road. I know I should not get my hopes up, that it might just be a freak accident, but it I can't help it. Every summer I get dreary, worrying I might feel barbecued. Now it is... well, almost nice. And then, there are these leaves, reminding me that my favourite season will come.