Sarah, for which charity are you raising funds with this hike? A link would be appreciated; these days even many free-lance "informal" hiking fundraisers will have a web presence, whether via a program like Big City Mountaineers or completely independent/ website.etc.
MSJ forumites have politely responded, with restraint, but this query is such a loaded topic that the OP has overtones of "Crystal," as old-timers may recall. A charity weblink would provide veritas, for a topic which has such gravitas.
That being said, if Mt. Diablo is the best you can access for heat acclimation and strenuosity for September Skyline Debut, ignoring the advice of seasoned veterans here will demonstrate hubris bordering on suicidal. A quick check of weather data for Mt Diablo (incl a Paid database of historical info) shows that you really won't have significant "Time at Temperature" to satisfactorily prepare you for what Skyline has in store.
You'll be jumping into the fire not from a frying pan, but from a pina colada.
Even if you hike on a day with the high of 87, the *hourly* temp profile is much more favorable than that of Skyline on Labor Day. And what if we get an inversion on the day of your hike? Fricasse.
Try this Mt. Diablo hike (North Peak) on the hottest day forecast. Carry at least eight liters of water.
Repeat. Without refilling H2O.
Prep trail, North Peak at Mt Diablo. Did I mention you should be able to do this ten-miler back-to-back, with eight liters of H2O? A total pack weight of at least 25 lbs would also help offset and self-assess the deficiency of training at lower elevation and temps:
"If you're bugged by the existence of a parking lot atop Mount Diablo -- the East Bay's signature peak -- you're probably just the type to check out nearby North Peak, which gets far fewer visitors and offers just as many awesome vistas.... favorite path to North Peak is definitely the hard way: five miles and over 3,000 feet of climb on some of the steepest trails in the Bay Area. The struggle has rewards beyond knowing you've walked from near sea level to one of the highest accessible points in the region. In springtime, the hillsides light up with wildflowers; in winter, rains cleanse the skies so you can see the snow-capped Sierra peaks hundreds of miles away; in autumn, tarantulas prowl the trails in search of mates.
Summer's about the only time when it's too hot to attempt this hike."
http://www.everytrail.com/guide/north-p ... state-park
July averages as the hottest month there, Aug Avg High is 85; you are finishing your training and heat acclimation during a period of anticipated *declining* temps
Mt Diablo forecast with peak /summit temp gradient (Centigrade/Celsius)
http://www.mountain-forecast.com/peaks/ ... casts/1173
Ten day forecast. If you are a grad student, you may not be able to hike on the warmest days, Tues + Wed, 87 F. Highs on Sat Sun are only 83/82, and the mid-range forecast shows a cooling trend before Labor Day (less accurate predictablility, JUST LIKE SKYLINE 3 weeks from now).
hourly summary example; not much time "at heat" if you do ten miles RT x 2 starting in the a.m. :
http://www.weather.com/weather/hourbyho ... inIndex=24
Skyline on Labor Day (for a first timer!!) with this level of preparation is a recipe for disaster, and puts rescuers at risk.
This is an example of why the Calif Legislature is considering legislation to expand liability for rescue reimbursement to hikers under certain circumstances (tipping point:Cendoya), and which provides impetus to those who advocate downright *closure* of certain trails and areas.
So, which charity are you hiking for? If you choose an alternate trail for your hike, as others have suggested, you probably will get additional support and contributions from the wide audience of this board. Post a link so we can contribute on your behalf. We look forward to a safe hike for you, and successful charity fundraising.
kind regards,
arocknoid