I made a wide-ranging jaunt through southern Ohio last Saturday, when temperatures peaked in the high 60's. One noteworthy ridgetop carpeted with chestnut oak had a small flurry of Mourning Cloaks; perhaps 4 or 5 flitting about. I also saw a first-of-year Comma, another species that winters in its adult form. Interestingly, like the Mourning Cloak, these two species also range broadly across Europe and Eurasia.
The appearance of butterflies is a surefire sign of spring and warmer days.