I've seen them in January before, after having lots of snow and well below freezing temps. If we get a period where it warms up above freezing, and it doesn't take real long, I'll start picking them up again in the woods.
Two weekends ago I was walking some property I just bought. Mostly all woods. The friend I was with and I picked up dozens of ticks on our pants, and I found one dug in a couple hours later. These are mostly deer ticks. They're like a plague around here.
Growing up I spent a lot of time in the woods. As a kid I was always out there running around, sometimes literally crawling through the woods and I never even really knew what a tick looked like until I was maybe 16 or so. They just weren't common. Every year or two a dog might pick one up. Seemed like around the year 2000 they really started to pick up, and then around 2005 or so they really exploded. They've been a plague ever since. Being that this is a very high Lyme's disease risk area, it's basically changed my whole lifestyle. I don't go out in the woods as much as I used to, and when I do I try to stay on trails. When I do venture off the trails we're checking each other pretty frequently for ticks crawling up our pants. I used to love grouse hunting in the fall. These days I prefer to wait until we have freezing temps to hunt grouse so I can feel at least reasonably confident I'm not picking up ticks along the way.
I remember when Lyme's disease was something you heard about but didn't know anyone who had it. Now I know lots of people who have had it.