Hi,-You don't mention if yur piping runs through an outside wall or not. The most obvious cause for this would be it is freezing up just in that section, the solution, if on an outside wall and you don't want to tear things up is probably to locate it and use expanding foam through a couple of small holes from the outside. If your walls are well insulated you might want to track down the junction point where it branches off your water supply 'cause all it takes is a 1 inch section to freeze. Have a good day,ss

Ok more specifics

Shower stall is on the second floor. Plumbing is branching off from the secondary bathroom that is more central to the house. No pipes are on an exterior wall. The adjacent tub has no problem.

I have Hot water coming out of the head. So it doesn't appear to be frozen. Or I dont think so. Its just a trickle.

Now granted this has happend before. Last winter. Only when it gets cold outside and windy. First time this year. Its just as cold today and my pressure is back but for how long.

Really is confusing.

Hello again! That is a great puzzler all right, I am sorry I cannot help but I just wanted to say it is one of the weirder things I've heard of. The only thing that comes to mind off-hand is something floating around in the piping but even that doesn't make sense since it seems to be a cold weather thing (I can't see wind having anything to do with it), good luck with it. Just another thought, is there a vent pipe that may be running close (as in next to) the shower pipe. I'm going to watch for a happy conclusion here 'cause it really is a strange one!

Have you recently repiped or do you have hard water problems? Maybe the flow restrictors in your valve are clogged. This was the case in our situation. Hope this helps?

Have you left the hot water flowing for a little while. If it was frozen maybe that would melt it. Just for the record I don't think that's what it is, but it wouldn't hurt to humor us for a while.

Devildog