Let me tell you what I've put my P226 through...
My OC holster is a Blackhawk Serpa duty holster, so short of a trench coat it will be fully exposed when I'm out backpacking. I've gone out climbing mile-high peaks in the dead of winter with the falling snow finding it's way into every nook and cranny it can. When glissading down the side of a mountain, I've had snow loosely packed up into the barrel (along with any dirt and debris suspended in the snow too), snow jammed up between the holster and myself along with snow lightly packed into places between the holster and pistol (never enough to make drawing difficult or impossible), I estimate that I've put on about 3-5 lbs from the snow being packed around my right side. Most of the snow is easily cleared with a quick unload and shake.
Last year I picked the "best" time to go for a 3-day excursion in the Alpine Lakes Wilderness. It doesn't rain at 4,000' in the mountains like it does in Seattle, it's a proper rainfall bordering on a downpour where a backpack rain fly becomes useless. Yes my pistol was out in the open during this getting absolutely soaked just like all of my other gear, which took a week to properly dry.
All I've ever done to dry it out is field strip and remove the grip panels, wipe it down with a rag, spray some CLP on just about everything, wipe it down again, followed by the typical cleaning after a few range trips and it keeps on shooting. I wouldn't worry about a little Seattle "rain" where you might be in it for an hour tops.