rhywrote a review of Marmot Phase 30 Sleeping Bag: 30 Degree Down on April 24, 2018
Familiarity: I've used it several times
I read a review on Outdoor Gear Lab which calls this a 40 degree bag, mislabeled as a 30 degree bag. I own a Western Mountaineering 30 degree bag, so I figured I had some basis for comparison. The WM bag is about 15 years old and contains similar quality down, but is not the water-resistant kind. I do a certain amount of backpacking in areas that get substantial condensation.
Anyway, I would probably call the Phase 30 more like a mid 30's bag, at least for me. This is a very light sleeping bag, and I used it with a silk liner, midweight base layer and a marmot driclime windshirt; pretty typical in my case. At temps in the high 30's I was not cold, but feeling a bit of a chill in the legs and feet. The next two nights were warmer and I did not even zip it up completely. Springtime weather, you know, can't make up its mind.
I got mine at the recent sale price. It's an ultralight bag; expect the zipper to be dainty and the fabric fragile. I'm used to it. If you need a bombproof bag you are going to have to carry the extra weight. Enjoy the journey.