There is no danger in storing LN in your garage. Your container won't be tightly sealed (a tightly sealed container full of LN likely is a bomb); gaseous LN will continually leak from your dewar. It's nitrogen, who cares?

The major risk with LN is storing it in enclosed spaces, as it can quickly asphyxiate you. So, like, don't take it in an elevator.

I'm not sure I understand what the ambient temperature has to do with LN safety.