Uncategorized Humidity causes the mushroom to pop out. September 6, 2015 SunDog Leave a comment It has been extremely humid in Duluth the past few days. I recall that Duluth usually gets lots of mushrooms and fungi popping up in the last few days of August and the first part of September. I’ve never heard the term “comfort index,” but I’ve been hearing it a lot now. When it’s humid it is really uncomfortable at 82 degrees.