I live in Massachusetts. I like you put the cars away December 1 or the first snow.
There are two rules of thumb. One says put a trickle charger to keep the battery charged. My rule is I disconect all my batteries. I have a 67, 71, 2011 and a 2013 Mustang. The threat of a fire or a short developing scares me. There are some who feel the computers will get goofy. I have not had that happen. When you drive the car in the spring the computers will re-adjust.
My 2008 Corvette has the battery dis connected more than connected. I drive the vette about 30 miles and all is well. My 2011 Pace Car (trailer queen) has not shown to have a problem and that battery is always disconnected.
My cars are stored in one of my buildings off site from my house. I cover the car and wait for the second rain storm in the spring.
Hope this helps.