Mold and mildew are usually considered “indoor” allergens, meaning that while they do exist outdoors the inside of one’s home seems to be the biggest culprit. Mold and mildew like dark and humid places – like the basement, around leaky pipes, under sinks, in baothrooms, in your flower pots. Some AC units can harbor mildew as well. In humid parts of the country (like the Southeast), outdoor mold and fungus can be significant as well.
Because most mold allergy comes from indoors it is very particular to one’s own environment, and is not really detected much by the “pollen counters” that get reported in the news. So no matter what the “mold count” is for that day, it probably doesn’t mean much to the average allergy sufferer because the “mold counts” in their home or work may be much different.
Them being “indoor allergies” are what also makes mold and fungus mostly a year-round problem, not affected too much by the weather. For the record though, outdoor mold counts usually temporarily go down in the hours after rainfall, but then spike right back up in a day or so because the humidity has them multiplying like crazy.