REI Zephyr +15

A great synthetic bag for the price. I sleep pretty warm so I stay comfortable in this bag below 15 degrees (early January in north Georgia) with a knit cap and socks.

This might keep you warm in 45 degrees. If you add a fleece liner to it, it might work in 35. The only way I can stay warm with this in anything close to 15 degrees is to put another sleeping bag over it. I was freezing in Yellowstone when the temperature dipped below 25 degrees. I was freezing in Canada when the temperature dipped below 30 and was cold in Mississippi when the temperature was under 40. This might be a 15 degree bag if you sleep really, really, really warm or wear a lot of clothes when you sleep.

I was cold in the REI Zephyr when the temperature dipped to around 35-40 degrees and around 30 degrees (10,000 feet last weekend in August and first weekend in September in Colorado). At 15 degrees F, I'm sure I would be freezing.

(It was fine last year in August in Quebec (near sea level) and in Colorado and Wyoming (5,000 feet) when the nights didn't go below 50 degrees.) In other words, I think the 15 degree rating is unjustifiably low.

Also, while it compresses to a reasonably small size, a "tiny nub" it is not. My friend's down sleeping bag -- packed but uncompressed -- is half its size.

So there we are. It's about 30 degrees, rain/snowing and misirable. After drying off next to a roaring fire, we all go to bed for the night. Many of those with down bags woke up after three hours of sleep and shivered through the night. I stayed nice and toasty in my synthetic Zephyr.

At 2lb 10oz it's not exactly heavy and it compresses into a tiny little nub that could fit into a daypack!