The state of California perhaps has the largest number of locally produced classical concert content
Beginning with the north, KDFC out of San Francisco broadcasts the San Francisco Symphony. The upcoming schedule is available here. In addition, KDFC has recent broadcasts available for on-demand streaming.
The Central Valley’s NPR station, KVPR, broadcasts the Fresno Philharmonic, typically on the second Tuesday of the month. An upcoming schedule is available on their website.
KUSC out of Los Angeles broadcasts several local concerts on it’s SoCal Sunday Night program. The most recent broadcast is available to stream on demand. The Pacific Symphony has published a schedule of it’s appearances. The Los Angeles Philharmonic currently has a schedule posted from last year.
In San Diego, KPBS-FM broadcasts the San Diego Symphony. The upcoming schedule is available here.