Rivnuts from Homestead, PA on 10/16/2022 10:34:59 AM:
My. Where to begin. Let's start with the weather. The average daily high temp in August is 83 with an average daily low temp of 64 with highs of 88 and lows to 58 providing a wider, but less probably band. You can expect some precipitation on 10 of the days in August with an average total monthly rainfall of less than 3 inches. Further, the humidity level is considered "muggy" on about 10 days during August.
With the exception of the first 19 miles out of Pittsburgh and a couple of miles approaching Cumberland the trail consists of fine, packed, crushed stone. The GAP trail will generally be smooth and solid except during or shortly after a heavy rain. Even then, while the trail may be soft, it has very few muddy spots.
The GAP is a rail-trail so changes in elevation are modest and smooth except for the bridge overpasses leaving Pittsburgh and a couple of short sections that deviate from the rail right-of-way. The uphill grade from Pittsburgh to the Eastern Continental Divide is almost imperceptible. The uphill grade is slightly more noticeable from Connelllsville to the Continental Divide but certainly not as dramatic as published profile illustrations would suggest. (Compared to Colorado, it's all flat!) That said, the ride down from the Continental Divide to Cumberland is a nice, long (23-mile) downhill ride making for an easy last day.
Lastly, as I've repeatedly suggested to new riders of the trail, take some time to learn some of its history and the region. There are numerous articles and YouTube videos of the trip. You'll appreciate and enjoy that which you will see if you understand what spawned the trail and what existed along the way.
If you have other specific questions, please post them.