How cold are nights in the upper elevations in mid-July?

[TigerFan]

I have a 5-day hike planned for July (7/18-7/22) from Tuolumne Meadows down to the Valley. Some feedback I've gotten on another forum has me second guessing our sleep setup. I'd really appreciate your thoughts.

I have setups (i.e. bag + pad) that I've been comfortable down to the low 40's and I had assumed that would be sufficient. I'm getting feedback that I should take 20-degree rated gear. I can do that but it would be a pretty big weight difference.

I do understand that nobody can guarantee these things and we could get a freak snowstorm. Just trying to get a feel for what's realistic.

Thanks!

[Vlado]

I camped at LYV on the evening of July 4th last year with a tent and a 0 degree rated mummy bag. The temperature probably dropped to upper 40's during the night (but I am not sure since I didn't measure it - this is my recollection of what the forecast for that night said). I had to completely unzip my bag and sleep like this (in shorts and a T-shirt) just because it felt waaaaay too hot in the tent.
The campground was full with people sleeping under the sky with no tents, so I don't think it was too cold.

[bill-e-g]

Once you get to the Merced River I'd say for sure what you
have now is definitely gonna be just fine then.

I use a 30 Montbelle all of July thru about mid-Sept.

What other clothes are you bringing. If you have fleece jacket and
pants you can just wear those and all the other clothes you have
to supplement your sleeping bag. If you're in a tent then you'll
probably be just fine.

What exactly is the bag rated at?

My guess at when you are going is that the coldest it will get is
40. Yeah, sure, people say it could get to 20 at 10K then but
that's doubtful. Look at the weather and you should know
ahead of time if some huge cold front is coming in.

If you're happy with what you have down to 40 I wouldn't worry about it.

[holz]

Bill is spot on.

Take your 30ish bag and be willing to wear more clothing should it get really cold. I use a 1lb 32F Mountain Hardwear Phantom. It is perfect for the Sierras in the summer.

[TigerFan]

Figures.

Well, I have 40-degree bags and 20-degree bags, and not really in a position to buy new bags for this hike. Guess I'll watch the forecast and decide at the last minute. We have two nights in TM before the hike so, hopefully, I'll get a good feel.

Thanks for the feedback.