Advice from Rob McKenzie concerning the Cajon pass, 2000/4/16
All I can think of is what's been learned over the years by local HG's and recently by some PG's that ventured there. It takes quite a storm to make it too windy to paraglide or hang glide but the Cajon Pass can have it's winds easily slide up the scale above 20 mph, and on up past 30 , .. 40, ... and even 50 to 80 mph. I know of days when it's blowing 15 mph at Marshall, 25 at Crestline and 50 just past the fire tower. Basically, the mountain BEFORE the fire tower has been decided decades ago as the end of the line even on light wind days. If I had a way to assure surface winds like a driver I trusted on radio up ahead then going through the pass would be fine.
Never consider a flight into the Cajon Pass, (north of the 15-215 jct) without some surface wind checks.