Silk liner only?

Depends. What is the 57F expectation based on?

Last month, my friends and I spent 4 days and nights in Canyonlands, Utah. The lows were forecasted at 50-55F all throughout. In reality, temp lows were in high 20's / low 30's — with frost dustings on our tents some mornings! The weather.com forecast was off by 20-25F!

For me, I would bring a summer bag and not just the silk liner.

Hm … I guess you are right. I am not sure how much I trust weather.com. Plus, that site was way off for the last trip I went on. Guess I'll take that bag after all :-(
S.

Smart decision! As the saying goes, "fool me once, shame on you. Fool me twice, shame on me". :)

Have a fun trip — and let us know if weather.com got it right — or not!

Will do … Missouri is calling me! (Yes, Missouri. Have never been there)
Cheers,
Sven

Take the bag–good idea.

I perfer wunderground.com, but they all get the same feed from NOAA. The NOAA weather stations are local (relative to the Zip code or the city), usually in the nearest populated area. You can get the data (wunderground.com has historical data in its Travel Planner section), then project it to the area you'll be hiking in. Consider the relative elevation gain (or loss) to adjust the temperature (typically subtract about 3.5 deg F for each 1,000' gain in elevation, depending upon the location, YMMV).

Think of the warm and fuzzy feeling the bag can provide you, literally :)