WHRB does not publish a program schedule for the "summer", that is, the period from Harvard's Commencement (last Thursday) until the beginning of the fall semester. On weekdays, you will hear jazz from 5 AM to 1 PM, classical until 10 PM, and rock overnight. The weekend schedule includes country ("Hillbilly at Harvard"), blues, classical, and R&B.
Most of WHRB's staff, being Harvard undergraduates, is away from Cambridge until September, as Harvard College is not in session.