3:15 a.m. on September 1, 2012 (EDT)
Usually hiking/camping in the mountains around LA is getting very warm by end of June. Many head for the eastern Sierra (faster to east side than west).
Pasadena to Lone Pine is quickest/shortest going I-210 North from Pasadena exiting in a few miles to go over Angeles Crest Hiway to Palmdale. It is a lot of mountain driving for around 40 minutes. Be sure to watch for the right turn to US 395 as you leave Mojave (good breakfast spot). If you leave around 4AM you will be on most of these trails by 9AM or so.
Cheapest gas is Mojave ARCO across from Denny's
Every town (and some wide spots) have access to the higher Sierra from US395 from Lone Pine up to Bridgeport. Many of the passes either start at around 6,000 (the ugh passes, like Taboose, Sawmill and Shepherd) or 9,500+ feet. Army, Kearsarge, Biship. They all lead to Kings and Sequoia NP at the pass. Lakes and great scenery usually within 6 miles or so.
You will need a Wilderness Permit for all of these trips reserved ahead of time. White Mountain Ranger Station in Bishop or Lone Pine Interagency Visitor Center.
Get "100 Sierra South Trails" guide from REI on Santa Anita off of 210 East. Tom Harrison Maps (.com) are good. Other end (north) on Santa Anita is 14mile r/t hike to Mt Wilson.
You can usually get to 11,000' by mid June at Cottonwood Lakes. First sticking snow is around Thanksgiving (give or take). High season is July and August but good overnights up thru October - cool tho.
Lone Pine: Destination Cottonwood Lakes and Army Passes (New and Old): Trail head starts end of 26mi curvy road at Horseshoe Meadows. Trail to the lakes and Army Pass starts around 10,400'. Be sure you are not taking trail to Cottonwood Pass which is about 1/4 mile farther along the road. First lakes are at 11,000' and about 6 miles in. I like Muir Lake for overnight. There is a use trail between Lake 1 and Lake 2 that will get you over to Long Lake in the other drainage. I prefer Old Army Pass especially if heading for Mt Langley 14,000'+ (a good day trip leaving early) from the lakes. Visitor center has a map that shows location of abandoned OLD Army pass trail. Langley trail is dry so take plenty of water. There is a trail junction to Army Pass. Stay to right not crossing meadow to get to lakes.
http://mapper.acme.com/?ll=36.49570,-118.20362&z=14&t=T
Independence: Destination: Kearsarge Pass and the lakes beyond. Trail head at roads end in Onion Valley. You can also investigate Golden Trout Lake and summit Kearsarge Peak. Lots of abandoned mining activity at the higher reaches of the mountain. Once at K Lakes you could head over to Glenn Pass and Rae Lakes for a long day trip. Good fishing usually at the lakes. There is a 4-5 day relatively strenuous loop here that includes Shepard Pass. Catch the trail head on Symmes Creek from the Onion Valley road - about 2 miles south. Thumb a ride up/down from Onion Valley to complete the loop.
http://mapper.acme.com/?ll=36.76804,-118.36164&z=14&t=T
Big Pine: Destination: Big Pine Lakes nestled below the largest glacier in California. Trailhead near Glacier Lodge. Take a couple of nights trip to explore the entire upper drainage of Big Pine Creek and even up North Fork to an over look up between Puzzle Peak Gendarme Pk. Or even Rainbow Pass.
http://mapper.acme.com/?ll=37.12111,-118.48180&z=14&t=T
Bishop: Destination Bishop Pass, Dusy Basin and perhaps Knapsack Pass as a cross country. Trailhead from South Lake. Long Lake is about 3 miles, pass is 7 and 8 or so to upper lakes of the basin. Many other lakes to explore if you don't want to go high and long. This leads to the back sides of the 14'rs out of Big Pine.
http://mapper.acme.com/?ll=37.12351,-118.53767&z=13&t=T
From North Lake is Piute Pass and the grandeur of Humphrey's Basin and the high Sierra.
http://mapper.acme.com/?ll=37.23566,-118.66273&z=14&t=T
Lake Sabrina also a trail head of significance.
And many many more.