outdoor x10 plug?

I have never seen one, when designing holiday plugs in homes there are two ways to do it properly. The X10 plug modules, I usually use Leviton, are setup that down stream circuits can be switched by the X-10 circuit.

1. You can simply install the plug in an outdoor rated enclosure.
2. A better route, get a 2 gang receptacle, install this indoor in the garage. In this two gang receptacle, install the x10 plug (this will switch all downline plugs as well in the circuit) and a GFCI in case one of the lights grounds out, the GFCI will be there for protection. Than daisychain your lights from the box using Romex. Be aware of wattage ratings"
3. If you really want to go all out you could install relay on the dedicated holiday lights electrical circuit and use a X10 flash module to trip one or more circuits.

So be aware if you are on of those who likes their yard to be seen from space during the holidays, watch you electrical ratings...

A. 15 amp circuit breaker is rated for up to 1600 watts using 14 gauge wire B. 20 amp circuit breaker is rated up to 2100 Watts using 12 gauge wire C. etc.. figure maximum watts using this formula "Amps multiplied by Voltage {120} multiplied by .9 (10% safety) = rated wattage for circuit"

Another option I've used is that there are clear plastic outdoor outlet covers available at Home depot, etc. They're designed so that cords plugged into an outdoor outlet can be provided with a cover, and the brand I used at my last house could fit a std x10 module. Take a X10 module with you when you go to home depot.