Will audio gear be ok in unheated house

I have a cabin in Michigan’s Upper Peninsula, it is relatively new construction well insulated and well sealed. I have some older equipment, Antique Sound Lab tube integrated, older DAC, and Vandersteen 2Ci, which I have been using there for several years. In the winter the cabin is unheated, and it typically is in the 30’s inside.  Only in the coldest weather does it drop into the 20’s inside. I know this since I have a weather station that has multiple sensors so I can monitor indoor and outdoor temperatures and humidity from my primary home. I do put out desiccant, specifically Damp-Rid, but it doesn’t do much. In the spring there is still desiccant and some liquid (when the desiccant absorbs moisture it forms a weird liquid in the bottom of the container).  The humidity is typically 50% - 60%, not great but ok. So far no issues with any of the equipment. If you know the humidity is higher or you just want to be extra safe one alternative is a desiccant from hydrosorbent. I’ve used it to protect woodworking tools. You do have to put the item in a sealed container for this to last several months, might be an issue for bigger components, but it works for small items.  Good luck!

Rather than using garbage bags, use moving size cling wrap to wrap your gear. It can be purchased on Amazon or at Home Depot. The 20" wide rolls work well for audio components and speakers. I use it to store my audio equipment that is not currently being used. I wrap two or three turns length wise and width wise and it forms a good tight seal that will keep out insects and moisture from anything short of full on flood submergence. I also use it for extra shipping protection when I sell gear.  

Beginning to sound like it's just easier to take your speakers with you!

Peace of mind knowing they're safe.

In the long run, leaving your stereo equipment in an unheated home where the outside temperature drops below freezing and/or below 50 degrees where dampness exists, is not a good idea, and eventually will damage your equipment.

Fwiw, I've left my porch system (Integra receiver and disc changer) outside in a cabinet through ten Chicago winters and it still works fine. Now, I wouldn't be so cavalier with high-end gear, and I don't recommend it for others, but there you go.