The adapters are fairly reasonable ($15-$25 for most on ebay, search NPT NST), the only issue is there is more than one standard of fire hose fittings, although the most common is NST (same as NH) which is National Thread, there are others you may find particularly in older hoses as some major cities kept their legacy non standard connectors for a VERY long time, some like NYC of CH may still have the legacy hoses, I am not sure. Or course there is also the alternative of removing / cutting off the connector and just attaching it with a host clamp.
Ike