While April is traditionally one of our rainiest months, the end of April puts you well into Spring and can offer some very pretty days with temperatures occasionally reaching the low 70's, but usually in the 60-degree range. Nites can drop tempseratures into the '40's. By the end of April, we will most likely have switched from Eastern Standard Time to Daylight Savings Time, which means an additional hour of daylight. It probably won't get dark until around 7 pm or later.
Depending upon what you enjoy doing, the end of April is a good time to visit the Brooklyn Botanical Gardens as well as the Bronx Zoo. The street festival season won't have started yet, but outdoor flea markets will be up and running, the Yanks and Mets will be playing baseball and, if the weather is nice enough, a few restaurants will have opened their sidewalk cafes.