Im doing my first big multiday hike…and I have my heart set on JMT. But I have off only until 3rd week in July and I am off on the first month of June…I am aware of the weather of the JMT in June but I was wandering if I could get away with hiking from Whitney to the Valley…as far as the weather…any advice would be helpful…
Cor
JMT in June? I’d recommend pushing your hike back until July. It can be done but its going to brutally tough and navigation will be difficult.
TwoCan
Hard to say what conditions will be like next June/July. 2010 wasn’t great and this year it was brutal–I did a section from Bishop pass south to Whitney starting Aug 1 and ran into dicey pass crossings due to snow. By Feb. 2011 you might have a better idea of what conditions might be though the Sierras are always unpredictable. Snow in Aug. is not unheard of. Also going NOBO is not the easiest–getting to Mt. Whitney, Forrester and Glen passes at the beginning of your thru will definitely get your attention. Consider doing a SOBO. Good Luck
Still Lookin’
We did the JMT this year starting southbound on August 14th. Because of record snow fall in 2011, every pass still had snow on it; however, it was easily manageable. Also, we only had to ford several streams during the entire trip. It was different though for hikers who started mid-July. They encountered many more streams that they could not rock hop or log cross especially in during the afternoon snow melt.
Hikers that started in July also incurred more rain/hail downpours. We only had one evening of a brief light shower. The entire trip was almost blue sky and chilly nights around 40 degrees. We did have one night where it got down to 31 degrees just south of Taboose Pass Trail.
We also saw no bears and very little wildlife except many marmots, birds, and a lone coyote.
Best option, try to change the dates of your vacation otherwise hiking in June/July might be to risky. Best of luck.
NedtheFed
Ned
I disagree with some of the above. The past 2 years have been high and late snow years, but the average Sierra year is not all that impassable in June. There is snow for sure, and the going is slower, but generally the weather is great in June, the mountains are at their most beautiful, and in most places NO MOSQUITOS yet.
The keys are: have some experience hiking in snow and be a decent topo map reader. Make sure to time Mather, Glen, and Forrester passes in the early afternoon when the snow is soft so that you’re safe (Those are the steep sometimes scary passes.), and consider starting from Kennedy Meadows and going northbound so that you can follow tracks from the PCT thru-hikers.
Of course if it’s another snow year like this year, you might be screwed. But about 9 out of 10 years you’re good.
markv
The one thing that I did not like when I hiked the JMT in early season was the mosquitoes. It took three weeks and terrain’s snow condition was OK in mid July 2010. That was my only regret going early (IMHO). Next time I hike the JMT, I’ll leave in mid August, preferably an average snow year (fingers crossed).
UncleHank
You can do it. I’ve done the JMT section of the PCT three years in June (start northbound from kennedy meadows south circa june 1-3rdish, finish near tuolumne around the end of june) and yeah it’s snowy, but it’s really not that bad. There’ll be PCT hikers out there going northbound if you’re looking for company at least as far as tuolumne. And I’ve even seen sobo JMTers out that early, too. Of course, these were two average and one high (2010) snow year and the high snow year was definitely a lot more difficult. But it’s definitely do-able.
Joker
I have been studying the JMT this year with plans to try it next summer or the following, depending on snow fall. I am doing the Wonderland next summer too, so if it is a high snow year (What they are predicting) I won’t be able to do both.
I would look into going south bound, unless you are from a higher elevation. Going from sea level or a few thousand feet to 14500 is a big jump and you may be effected by the altitude. Starting north and heading south will give your body time to adjust to the heights. Remember climb high but sleep low. Not that you would want to sleep on the top of a snow covered pass! 
Well maybe…
If you do go with heavy snows, take a ice axe, they can be rented, and some kind of foot traction device, it will help alot. Maybe a GPS also, depending on your map skills, but I don’t know if I would rely only on the GPS, I have heard many stories about them not working quite right.
Finally, if their is a lot of snow, chances are that the trail between Yosemite and Tuolumne may not have any use and be quite hard to follow. Just some of what I hear about this year.
Wolfman
Wolf
Thanks Wolf…I really appreciate your time… I might go anyway…I need a challenge…and Im going to push it back to July 1st…I know it may still be bad but…hey well see…any reccommendations on just part of the trail?
Cor