Yes, thermal winds in the afternoons in summer and fall.
Not hurricane force or anything, but gusts of 50 mph (45 knots) or more are not uncommon during Diablo wind events or storms. Gusts up to 70 mph (60 knots) have been recorded at times. Just this winter we had 90+ mph winds recorded in Sonoma (wouldn't have affected the current BART system, but still).
Some parts of the east bay are really friggin windy. I used to live on top of a hill near the carquinez strait and during windy season they'd easily exceed 60mph during a storm.
Like once every other year a bunch of fences would get demolished lol.
Only for the route to Marin, which Marin didn’t want and was never built.
That's not what the article says: "On aerial trackways during high wind events – which the engineers knew were not uncommon in places such as Contra Costa County -- the light BART cars could potentially tip over, the engineers hypothesized."
It does say later that it was also a consideration for running BART on the lower deck of the golden gate bridge.
Yes, I was objecting to the false "only".
Marin /did/ want it, but after the Golden Gate Bridge authority insisted that the bridge couldn't support the extra deck needed for BART there was a risk that if Marin were part of BART they'd be on the hook for the money without ever receiving service. That, unsurprisingly, reduced enthusiasm - and if a reduction in the Marin vote had dropped the overall bond vote below the required 60 percent, none of the system would have been built, so Marin was kicked out.