Good one....
I think it is pretty clear IMO that the receptical (in this case on the end of a cord) would need to be weather proof while in use,
(in a "wet" location) as it would be unattended while in use, and especially as it would often be in use in inclimate weather. (Storm = power outage)
If it were a "damp" location, I think it would be OK..... But would preffer a pin and sleeve connector over that one either way, as most are wheather proof anyway, and can have a weather proof cover for the cord cap. Not to mention a much better connection for this application. (i.e. "first make - last break" ground and neutral)
(
Commentary)
406.8(2) Other Receptacles. All other receptacles installed in a wet location shall comply with (a) or (b):
(a) A receptacle installed in a wet location where the product intended to be plugged into it is not attended while in use (e.g., sprinkler system controller, landscape lighting, holiday lights, and so forth) shall have an enclosure that is weatherproof with the attachment plug cap inserted or removed.
Section 406.8(B)(2)(a) applies to receptacles other than those rated 15 and 20 amperes, 125- and 250-volt, that supply cord-and-plug-connected equipment likely to be used outdoors or in a wet location for long periods of time. A portable pump motor is an example of such equipment. Receptacles for this application should remain weatherproof while they are in use.
(b) A receptacle installed in a wet location where the product intended to be plugged into it will be attended while in use (e.g., portable tools, and so forth) shall have an enclosure that is weatherproof when the attachment plug is removed.
Section 406.8(B)(2)(b) applies to receptacles other than those rated 15 and 20 amperes, 125- and 250-volt, that supply cord-and-plug-connected portable tools or other portable equipment likely to be used outdoors for a specific purpose and then removed.