Not all the Summer events are posted yet, but watch the site for FSGW that Artbrooks linked to. (There is not quite as much in the Summer, as many are attending festivals and traveling, but there is ALWAYS something.)

(I live on the Maryland side of the river, so am not as familiar with the facilities and routes, but it is usually not hard to get to the Metro (subway) and get to almost any area.)

Post more as you know more.