I understand that July/August is a monsoon season with a risk of a thunderstorm similar to July 29, 2011.
And what is a period of a good weather?
Can I assume that the most stable weather is from mid-August to mid-September?
Check weather.gov for Las Vegas, NV, and position the moving map to Mt. Whitney. You may need to zoom in one or two levels to see Whitney. Click it for a Whitney forecast. Then, in the lower right hand area, look for "Forecast Discussion" and click it. There is some weather jargon, but it is generally understandable. A southwest flow is dry and there will be no thunderstorms. A southeast flow brings moisture and the possibility of thunderstorms. Here is the current discussion:
.SYNOPSIS...
SOUTHWESTERLY FLOW ALOFT WILL KEEP SKIES CLEAR AND DRY ACROSS THE REGION THROUGH SATURDAY. OVER THE WEEKEND SOME MOISTURE WILL MOVE INTO THE REGION FROM THE SOUTHEAST FOR AN INCREASE IN CLOUDS. EARLY NEXT WEEK A TROUGH OF LOW PRESSURE WILL MOVE ACROSS THE REGION BRINGING COOLER AIR.
Remember that the mountains make their own weather and anything is possible at any time. Dress in layers and be prepared for the worst.
What is a likelihood of getting a thunderstorm or a heavy rain in September?
Actually I am trying to understand what kind of whether I can expect on Labour Day or a week after Labour Day.
I need this info to better plan my trip to California.
Yury,
September is my favorite time to hike. There is always a chance for a thunderstorm, but not as likely as July/August. I always carry a Marmot Precip rain jacket & pants. I use the jacket more for wind protection than rain in Sept. I can't recall the last time I used the rain pants in Sept.
The afternoons are usually warm to hot, the evenings are chilly after the sun goes down and the early mornings are cold (around freezing or below for a few hours). Be prepared for a wide range of temps in a 24 hr period. Layers, layers, layers.
The skeeters are minimal in Sept, although with the late snow melt this year, they may be around a little longer.
Wazzu
Yury,
I normally try and hike in the area some time during the 2 weeks before and after Labor Day. Though the days are a bit shorter than in mid-summer, but the weather is more stable, the mosquitoes are basically gone, and it's not nearly as hot (I just hiked the area in late July this year -- an departure from normal for me -- and because of the heat and mosquitoes, will probably not repeat that again, but will return to late Aug/early Sept in the future). Also after Labor Day, it is generally less crowded, not that being crowded is a big problem on Whitney, given the quotas.
So echoing the previous post, I would highly recommend the two weeks before and after Labor Day -- my favorite time in the area.
CaT
This year, the weater was super stable in February
Thank you CaT and wazzu,
I will try to come there one week after the Labour Day.
Yury
Early season snow storms have occurred rarely in September, but very little, if any, thunder storms. Watch the long range forecasts carefully.