I checked out the observing conditions at Montebello OSP tonight for the first time.
When I arrived, James Turley, Albert H. and a couple of others whose names I didn't note were already set up. Another six cars arrived after me, including Jay Freeman and Paul Sterngold.
James announced that the humidity was 87%. I responded that those conditions indicated a 13% chance that I would set-up my scope. The humidity quickly climbed to 97%. That left a 3% chance that I would set up my scope.
I got some good views of Io's transit of Jupiter through a 7" Intes Mak-Newt, and also through Paul's vintage 6" AP refractor.
I sat down in a lawn chair with my small star atlas and my 10X50 binoculars. But after an hour of tracking down a number of clusters in the Southwest (M2 & M73 in Aquarius, M15 in Pegasus, M74 in Sagitta, M29 & M39 in Cygnus among others), the pages of my atlas were quite soggy, and I couldn't put my binoculars up to my eyes without them fogging up.
Some hearty souls with good dew abatement equipment stuck around after I left at 8PM. Still for a first visit to Montebello, it wasn't bad. I can see why the west valley folks go there. It's a bit too far for me on an ordinary week night.