Capping a leaky outdoor faucet, good idea?
You could probably use a shutoff like this one as a temporary solution.



If it's still "temporary" when you winterize, I would remove it then.

Edit to add why it's temporary (as requested via comment).

Why is it a temporary solution?  Its a quick way to stop the leak, but doesn't take freezing cycles into account.  Outdoor valves are typically "frost free", and the portion of the valve that actually stops the water flow is either inside the heated area of the house, or deep underground.  A long stem on the valve allows the user to turn the valve on or off.  Diagrams of typical frost free valves appear below.  When turned off the portion of the valve outside (or above the fiostline) is allowed to drain.

As you can see, using the above as a quick fix won't allow water to drain out of the valve body (or in the case of the underground type it won't provide vent to drain underground).