In Canada, an outside plug facing down does not need an in-use cover. Is there a similar rule in the NEC?

This is from the '11 NEC:

406.9 Receptacles in Damp or Wet Locations.
(A) Damp Locations. A receptacle installed outdoors in a
location protected from the weather or in other damp locations shall have an enclosure for the receptacle that is
weatherproof when the receptacle is covered (attachment
plug cap not inserted and receptacle covers closed).
An installation suitable for wet locations shall also be
considered suitable for damp locations.
A receptacle shall be considered to be in a location
protected from the weather where located under roofed
open porches, canopies, marquees, and the like, and will
not be subjected to a beating rain or water runoff. All 15-
and 20-ampere, 125- and 250-volt nonlocking receptacles
shall be a listed weather-resistant type.

Hope this helps.

Interesting fact is the device has to be 'WR', although the wording 'in a location protected from the weather.....'

Does CEC require WR (Weather resistant) receptacles?

Thanks for the info.

Weather resistant receptacles aren't in the CEC. I never heard of them until now.