I have an SUV with a dying battery that's doing exactly that, and higher temperatures exacerbate the problem. New battery time.
I use a Deltran Battery Tender Plus on my garaged modern car, because the electronics kill the battery after a couple of weeks not starting it. It has a coupler that can be detached and covered, and easily tucked out of sight when using the car. Good for a garaged car. If yours is outdoors, there are solar chargers available to keep your car battery charged when the car is not being used daily. Sometimes I won't use mine for months.
I use a SSD as my boot drive on my computers, and use externally attached regular hard drives for large capacity storage that also have backups of the SSD's. I'm amazed that some people don't do regular backups at all, naive people think they will never lose data but they will.