Autumn officially arrived at 4:22 AM EDT (8:22 UTC) - 10 minutes before I woke up this morning. It's one of those bittersweet events because it mean Summer is over. The tradeoff is cooler temperatures. I don't think it's a truly even exchange :O
Aside from the weather, the days will be getting shorter with fewer hours of daylight. Soon enough, my post-work runs will be in the dark. That's one change I certainly won't be looking forward to with open arms.
But the big payoff of Fall is Color! I can't wait for the leaves to start changing colors - and falling (now raking them is an entirely different matter) - haha.