Daylight hours in October are way less compared to summer, so that is another effect.
Watch the weather closely -- if it is clear and no storms coming, then you should go. But otherwise, cancel your trip. Any storm coming in at that time should not be underestimated -- as Randy pointed out, he decided to turn around.
It is likely there will already be some snow on the trail, but hikers will usually pack it down several days after the storm.
The mountain will always be there, so you can try for the lottery again next year. In fact, any other year, I would suggest that you try earlier in the summer for a walk-in permit. They are pretty easy to get, especially mid-week. Only this year, with the parking restrictions due to road construction, walk-in requests don't get a parking permit for Whitney Portal. Parking will be back to normal next year.
If you continually watch Recreation.gov for permits, especially in the week following the current date, a few good people will actually release their reserved slots if they can't hike, and you can reserve a permit. Reserved permits will get you a parking permit at Whitney Portal. Here's a link for Sept 1, you can bookmark it, or change the date within the link as you need:
http://www.recreation.gov/permits/Mt_Whi...amp;entryType=1
