Best times to hike the JMT this year?

August and September could be smoky this year.

billy

Your best bets for the JMT (in my opinion) are mid July through beginning of September. The catch is if you go to early, you will have issues with mosquitoes, and possibly snow on the passes. if you go to late, you will have MUCH less water in the streams. If you go even later you run into the possibility of getting snow dumped on ya and colder temps. If you plan to do a late trip, also consider which resupply locations will still be open. For THIS year, I think earlier would be better, since its already so dry and there will be a good risk of fires onces the thunder storms start.

Weights after resupplies is tricky because it varies so much from person to person depending on what kind of food they bring and how many days worth of supplies they are planning on bringing. But I think the general rule of thumb is 2 lbs of food/person/day.

2 lbs of food per day is a lot.
it is pretty easy to achieve a weight of 1.5 lb per day.
and lower is not that hard if you truly want to go UL.

Agreed with both Billy and Dan–increased wild fire risk in August and September, and if I were doing it, I'd try for a late July start. I think the mosquitoes will be tame by late July this year–at least, tame by July-in-the-Sierra standards. But if my schedule didn't permit me to start in late July, I'd start in August or September or whenever I could, and just be prepared to be flexible in the event of wild fires. I mean, something like the Rim Fire couldn't happen two years in a row, could it (…Adam searches furiously for some wood to knock on…)

What do you mean by "how late could you safely hike it this year"? If you're referring to wild fires, well, as I mention above, it will be a gamble–with the odds slightly tilted against you in the late summer, this year. If you're referring to the onset of next winter's snow, then it's no different this year than any other–nobody knows. I've been snowed on in September, but I think significant accumulation doesn't (typically) begin until October.

I average 120 cal/oz of food. You can do a lot better than that. Especially if you eat only olive oil. I only try a little bit to optimize for weight, but mostly I eat what I want to eat, weight be damned. String cheese is only 80 calories per oz. But I'm from Wisconsin–I have to eat my cheese.

And just for some data points, when I hiked the JMT, I planned to carry 7.4 lbs of food between Happy Isles and Red's Meadow, 6.9 lbs between Red's Meadow and Muir Trail Ranch, and 12.2 lbs between MTR and Whitney Portal. I don't know what I actually carried–at each resupply, I kept some of the food I still had with me from the last resupply, took some of the resupply, and threw the rest in the hiker boxes. That planning was based on taking 14 days, but I did it in 11.