With due respect Rybir, you're doing what I do way too often: Over analyzing! Just pick a spot to hike and go hike. Have a lower-altitude backup plan in case when you start hiking the actual weather forecast, the short-term forecast, is looking bleak.
Relying on a farmers almanac or other hocus-pocus forecasts for longer term planning is downright silly. Just my HO.
Here's an excerpt from a CNN article:
http://www.cnn.com/2015/08/19/living...accuracy-feat/
"Both (the Old Farmer's Almanac and its competition, the Farmers' Almanac) claim high accuracy rates (around 80 percent) but have never published evidence backing them up. They lack transparency and keep their methods 'closely guarded,' " wrote the Washington Post's Jason Samenow in 2013.
Added Dennis Mersereau of Gawker's "The Vane," "The Old Farmer's Almanac is to meteorology what astrology is to astronomy."