It appears to have been around 95 degrees in Sierra Madre when I started a brief hike up the Old Mount Wilson trail. It wasn't that hot, or it didn't feel that hot, but it was definitely hot. How hot was it? I personally spotted snakes and lizards falling out of trees and sizzling on the trail.

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I only went to First Water, for about 2.6 miles round trip and 1000' of gain. I wasn't exactly being stingy with the water, and I drank over 2L going up and down. Total pack weight was about 22 lbs.

There was enough intermittent shade on the trail and a slight breeze so it wasn't that bad. Going up a trail without any shade would have been a different matter.

The upside is that I saw less than a dozen people on the trip. On a cooler day it could have been twice that number. And, there was no one else at the pool at First Water. So, it had that going for it.