A few years ago it was particularly bad: I went camping on my dad's land in northern New Hampshire one weekend and we had literally a dozen ticks crawling up our legs within five minutes of arriving. When I awoke in my tent the next morning, the outside of the tent had dozens of ticks clinging to the outside netting, trying to get in. It was impossible to walk anywhere without getting several ticks on you. None of us, including my dad who has lived here 60+ years, has seen it that bad.
In contrast, we were up at the same area a few weekends ago and we spent three days walking through the woods, camping out, and wearing shorts the whole time. The three of us had a total of 2 ticks the entire weekend.
I'm very curious to know what's influencing their numbers.