I gather from the destinations (Mailbox Peak, Gothic Basin) that you live in or near Seattle. That is soggy country! (So is Portland where I live.) Not only does it rain a lot from October or November through May or June, but the snow is soggy, too. I used to X-C ski wearing jeans in the Rockies where the snow is dry, but I'd never do it out here on the soggy West Coast!

I gather that the group he has gone with is one of the Meetup groups, not the Mountaineers who supposedly check. When I belonged to and led trips for a similar club in eastern Washington, I always checked! I do know that at least one of the Seattle Meetup groups has ended up in a disaster situation where they had to be rescued, and at least one member of the group lost toes due to frostbite. They took a 2-person tent for 4 people; they didn't keep their insulation dry and they didn't check the weather forecast (hyped by the local TV stations as the "Storm of the Century," which we get every 2-3 years, but still should have been heeded). Your friend might want to read at least the first part (plus some comments) of this extremely long thread on nwhikers.net

The old saying about taking a horse to water but can't make it drink definitely applies here. Either you refuse to take the friend without proper gear (which is what I'd do, because I'd care) or you can carry emergency gear for him (which I wouldn't do because I can barely carry my own gear) or you can let him suffer. Now that the PNW's winter has finally arrived after a very dry November, December and January, you can probably guarantee that the friend will be wet and miserable unless you don't go out until July.

I'd personally practice tough love and risk losing the friend, but only you can make that decision!

I note now that your hike was Saturday. It didn't rain on the beach (I was at Westport, WA with family), so maybe you lucked out? Too bad the trip wasn't Sunday or today! Anyway, do let us know what happened! Thank you!