Michigan outdoor grower here and I was concerned about rain the first time. Im on my 4th grow and all of my plants at some point have been exposed to torrential rain, 60 mph winds, 35 degree temps and hail.
The two biggest problems have been branches breaking due to the added weight after a soaking and mold due to the moisture. Be prepared with velcro and stakes of some sort. Use an electric blower from a distance to dry things out.
Rain will not harm your buds or the trichomes all that much. It does not wash them away like you may think. More so, the force of a heavy rain may break the trichomes off and then wash them away, but they will grow back as long as it doesnt happen right before harvest.
Growing outdoors is a challenge so be patient and realistic. These plants have been growing in the wild for thousands of years so dealing with the elements and bugs is in their genetic. (lol, my last post was just about something eating my leaves 3 weeks into the grow which is stressing me out. The plant still has 30 other intact leaves on it, but still I think that one leaf is going to affect the outcome 3 and half months from now) Good luck.