i've never left minnesota so i cant say for certain, but i sorta think the whole mold thing is a bit overrated in many areas, i've had fat buds undergo weeks on end of rain and if not rain very near rain, and have never had an issue with bud rot. them damn caterpillers are another story entirely but but rot has never troubled me and i've found over the years in this climate that, in the midwest mind you, if you are lucky, and good enough, to get a crop, or single female plant, to survive untill october you should count your blessings, and if you're not growing a strain like mighty mite or lui mold should be the least of your concerns, frost is your main enemy, not because it will kill your plants,(because excluding exreme conditions it won't) but because it is a precurser to extended cold periods and increased low temps.
a light frost every week or two durring late budding wont kill your plants, nor will a rainfall, but a heavy frost, say, 27 farenheight or below for a few days straight will lead to a cannibus casualty, just as quickly, and unlikely as rain or heavy humidity could cause if it happens for an extended period of time.
bottom line is, plants are plants, an amazing genus based upon millions upon millions of years of evolution, rain isn't new to this world, nor is frost, and plants will survive it better than we could in the same situation...