Just recently the hatch on my 2011 Acura MDX started immediately power closing after power opening. This only happens when it is very cold. After a little time in the garage the hatch opens on command and stays open until commanded to close, as it should.

 

Not sure where you live, but I am going to assume that you have snow currently based on the cold. My guess is that snow is getting into the crack at the top of the tailgate and when you park it inside, it melts and opens freely, but when parked outside it gets cold and freezes again. Another thing could be that the lift gate module is getting too cold and malfunctioning. A couple weeks ago I put my iPhone in the door handle (used to close the door on the inside) in our santa fe and it was apparently so cold that the phone shut off.

 

Thanks, RDX10. I am in Montana. You may be right about cold but probably not about snow. There is snow but it has been below freezing -- 26 degrees -- in the garage and the snow hasn't melted. It has been minus 2 to plus 15 degrees F outside when it wouldn't stay closed. It has warmed up now so I cannot reproduce the failure for a mechanic.

 

When we were getting -30 here, the hatch was having a very hard time opening, but thankfully no closing on it's own. I say that with heavy stomping on wood because the MDX feels like it is out to get me lately lol.

 

The tailgate struts also work harder on snow (They weaken) so add everything up and the Tailgate must be closing because it senses too much restriction (Like it was bumping into something).. But in reality the Tailgate Struts must be too weak to open the tailgate completely... Inside your house (Hotter) they might have enough force to open it up normally.

My advice will be to replace the Tailgate Struts which are inexplicably cheaper than the Hood Struts.