Hi Michael,

I have been enjoying your adventure posts immensely; keep up the great work!

I lead hikes for the local chapter of the Sierra Club in Tucson, and in mid-August we’ll be doing a 7-day backpacking adventure in the High Sierra. We’ll be accessing the John Muir Trail, with elevations ranging from 9,000 to 12,000 feet. How cold can it get at this time of year and what clothes/protection would you recommend? Would a light windbreaker over a fleece with gloves and hat be sufficient? Or would you recommend a down jacket, etc.?

I’d appreciate your feedback! Thanks and regards,

Tucson, AZ

Hi Mitch,

Thanks for following The Big Outside, glad you enjoy it.


Hiking the John Muir Trail below Cathedral Peak in Yosemite National Park.

Hiking the John Muir Trail below Cathedral Peak in Yosemite National Park.

My JMT thru-hike was in late August, so we saw the conditions you will probably encounter. I would expect low temps from the mid-30s to mid-40s, and possibly dipping below freezing. Evenings tend to be milder and early mornings the coldest time of day, until the sun hits your campsite (which isn’t early when you’re surrounded by big mountains).

I carried a lightweight down jacket that was under a pound, and I prefer that over a fleece jacket because the puffy jacket is lighter and more compact, and I don’t need it to be breathable because I’d never wear it on the trail in summer. How warm a puffy jacket you need varies between individuals, of course. But I’d say that, for the time of year you’re going, people who get cold easily would like a down jacket that weighs around one pound or slightly more, while people who don’t get cold easily will probably be fine with a down jacket in the 10- to 12-ounce range. Weight is a pretty good indicator of warmth in a down jacket, although down quality is also a factor. You may want to check out my down jacket reviews.

A great weight-saving option that I recently reviewed is the Sierra Designs Mobile Mummy 800 sleeping bag, which converts to a long down jacket, letting you eliminate the weight and bulk of a down jacket.

When we started hiking in cool, early-morning temps, I just wore my light rain shell until I warmed up, which usually didn’t take very long. But a lightweight fleece vest is a good option if you’re hiking in early morning, and its added insulation allows you to supplement it with a lighter down jacket than you’d otherwise need in camp if you didn’t have the vest.

I also carried a warm wool hat and light gloves for hiking or being in camp on chilly early mornings.

By the way, as you may know, the High Sierra sun can be brutal, especially in the afternoons. I find a wide-brim hat is a must, and I actually prefer taking a good, shady break by a lake for a swim in the afternoon and hiking a bit more in early evening.

I think mid-August to mid-September is the best time of year in the High Sierra: fewer people and mosquitoes (the latter can be very thick, especially near any standing water when there’s no wind) and pleasant temps.

Have a great trip. Let me know how it goes for you. Thanks for writing.


Hi Michael,

Thanks for the excellent information! I’ll check out your reviews of down jackets and the Sierra Designs Mummy sleeping bag.

Happy trails!


In Ask Me, I share and respond to a reader question. Got a question about hiking, backpacking, gear, or any topic or trip I write about at The Big Outside? Send it to me at mlanza@thebigoutside.com, message me at facebook.com/TheBigOutside, or tweet it to @MichaelALanza. I will answer the ones I can in a post, using only your first name and city, with your permission. I receive a high volume of questions, so I cannot always respond quickly.

—Michael Lanza