I just heard from guidebook author Nancy Pallister who has been in the Winds for over 6 weeks. It has been an unusually mild and dry summer in the Winds. Whether this abnormal weather continues is another issue. Fire danger is extreme and she reports a fire burning in one of the most isolated (and beautiful) areas of the Wind River Reservation, just east of the Continental Divide. Expect smoke.
I would normally expect most clear nights from mid-August on at higher elevations to be below freezing, with some ice in water bottles left outside. Note that there is no weather station in the Winds except (I believe) Elkhart Park, so any data you see for Titcomb Basin is simple theoretical projection based on altitude. IMHO, theory doesn't keep you warm on a cold night; a few more ounces of down will do a better job.
A few years ago it snowed almost a foot in Titcomb Basin two successive weekends in the first half of August, and people with thermometers reported temps in the teens F when it cleared. I know that Elkhart Park reported 22*F the morning after the first storm (I was up there talking to the ranger). My dog got sick and I had to abort my trip, or I'd have been at 11,000 feet when the second storm hit.
From late August on you can expect freezing weather on clear nights and some snow with most storms at those elevations. Whether it happens this year, who knows, but I wouldn't want to be out there unprepared.
One thing I've learned from living in the Pacific NW for 40 years is not to trust weather forecasts more than 24 hours ahead. All that ocean west of us doesn't like to follow computer models. The same thing is true of high mountains, which make their own weather. For what it's worth, the NWS predicts possible freezing temperatures east of the Cascades tonight.