Last year, on a 9 day trip down to the Kern from Horseshoe Meadows, up Rattlesnake Creek, over to Big Arroyo at the end of September, I encountered 2 days of snow at Big Arroyo and the HST. Granted, the snow depth never exceeded 3 to 4 inches, but it was enough to slow me down, drop the day and nighttime temperatures significantly!!!!
I knew the possibility of the change in weather prior to the trip and planned accordingly. Sierra weather can change quickly.
