If they are very fresh when you first get them they will keep in the refrigerator for quite a while. I've had some for at least a month in the past, with no loss of flavor.

Being the time of year it is, if it's colder than 50F outside and you have a garage that in my experience keeps citrus juicy for a long period of time. My garage becomes an extra fridge in the fall an winter months. I keep a thermometer on the wall and it is always a nice cool temp for storing produce.

Awesome! Thank you so much.

If you are going to store for longer than several days the crisper drawer of your fridge is the best place, and shouldn't affect the taste. The grapefruit will be juicier if it is warmer, so you may want to leave a few out on the counter for more immediate eating.