High Sierra Weather

[lkissell]

I am planning a backpacking trip that is going to originate at the Devil's Postpile and will end at Lake Italy. I will be following section three of Steve Roper's Sierra High Route, but I will be traveling north to south.

I will be arriving on 8/23 and leaving on 8/31, and I'm trying to determine what type of weather I should anticipate at altitude. I realize that the weather is unpredictable, but I would like to know what the average temperatures are for this area (between 8,000 and 12,000 feet).

I have the average temperature date for Mammoth Lakes, CA, but I can't find anything for temperatures on the trail.

I appreciate any help that can be offered.

[freestone]

Sierra weather and California in general, run in patterns.
A snow storm and a long hard coldsnap in your timeframe would be rare, but a monsoon outbreak is quite possible. This would include afternoon episodes of thunder, lightening and scattered downpours. These rainy periods can last up to eight days, usually followed by an equally long period of fair weather. That said, about two weeks before your trip, you will be able to access medium range forecasts via the NWS, that will include your timeline. Beyond two weeks, prepare for the worst, hope for the best.
I usually show up at the trailhead prepared for the worst, then repack and pare off items that would be considered overkill, based on the three day forecast from the NWS. So in summary, start studying the longrange forecasts, look for patterns, and remember that the NWS is pretty darn good between day one and three. If all else fails, consult the Dweebs, they haven't let me down yet...

http://64.29.226.243/dweebprinter.htm

[sierra cyd]

Hmmmm, as for temperatures, as a rough range I'd say the lows could be around freezing, and the highs could be around 70 degrees F.

As freestone mentioned, there is a good chance of thundershowers which often stick around for many days straight, including wind, rain and hail which can be very cold especially at that elevation with the exposure, so a waterproof-breathable rain suit is a necessity in my opinion.

Since you'll be out for 9 days it is a good idea to take the gear you'd need for the bad weather even if the "3 day forecast" is sunny because things change fast in the mountains.

Have a great trip! I've been through that route and it is beautiful.