Spot the cold front

Good thing I was inside and could close the windows when the temperature dropped 8.3°C (15°F) between 3:35 and 4:35 pm:

I got the dogs out around 2 (I'm dogsitting Butters again), and they have fur coats, so they did not mind at all. It's now just over 9°C outside with a forecast low of 5°C tonight, yet I had the windows open last night. Spring in Chicago continues apace.