As I recall the WDW monorails have AC units and the windows won't open, The older Mark V's don't have AC except in the ends and the windows open allowing cross ventlation. Sounds like they had the same plan for the Mark VII except they forgot about the open window thing and tried to do it with forced ventlation. That would require fairly high CFM to keep the temp inside with in a few degrees of outside.
If a WDW monorail stops it can be real hot, real quick.
Living on the East Coast, WDW is the park I visit the most with my family - usually in the 1st quarter of every year. Even in January and February, I have never been on their monorails where the air conditioning wasn't running.
Florida is just too hot and humid to open the windows. I would think California has times during the year where they have the same problem.