Salty reports weather has been great, though very cold at night (in 30's).
That is not very cold. We just returned from one of the warmest JMTs I can remember. All night temps were a warm 32-40. I can recall plenty of trips with temps as low as 18F and frozen water bottles multiple days, even in early August.
He will be fine, best thing to do is just get up and going and climb those passes even faster in the cool mornings.
Best wishes.
