There was a thread back in early February from someone who had experienced really bad no-seeums in late January on CC, but we were there just a few days after they were, and did not see/feel a single solitary one. Somebody mentioned that it might have to do with what the weather is like on that particular day, and someone else mentioned that they all hatch at the same time and live only a short time, and it's completely random when they might "strike".
I know that's not much help to you, but bottom line is that they could be horrible while you are there (so take some stuff and be prepared), or you might be fortunate like we were and have NONE at all. Hope it's the latter for you!