Not in this day and age. United stranded me in Houston last year after leaving late from LA... said it was because of the weather and politely told me to "shove off." Well guess what, it was another perfect day in LA that day. If work hadn't paid for everything I'd be very angry. I'm still angry but busy and less motivated to fight.
A company that could do the fighting for me could be helpful. Even if they didn't produce a profit for me, I'd consider using it out of principle.
Weather upstream from your flight can still be responsible. If the aircraft your flight is going to use gets delayed due to weather earlier in the day, that's a weather delay, even if you had clear skies at your departure.
Airlines aren't responsible for weather delays, full stop.
Not even. If air crew is unavailable because a previous flight ran long due to headwinds and they are out of allowable flying hours for the day, week, or month? That's "weather-related" and you get nothing.
I agree, I could have been clearer by repeating the exclusion for weather delays on one or more line items. I'm sure there are even borderline cases where a denial by the airline might be questionable and your only course of action would be to repeatedly and/or strongly state your case, escalate the matter up the chain-of-command, call/file your case with the government (e.g., DOT ACPD), file a request for arbitration (i.e., if your ticket requires), file a small claims suit, etc.
A company that could do the fighting for me could be helpful. Even if they didn't produce a profit for me, I'd consider using it out of principle.