If you want a little getaway from the city without having to cross the Maryland Bay Bridge or drive all the way to Pennsylvania, you might want to consider the St. Mary's County Fair this weekend. Sunday looks like the best driving day, with rain clearing early. St. Mary's County is Amish country, so watch out for horse-drawn buggies as you drive the rural roads, especially Route 5. A county fair in a rural setting with Amish presence AND a farming community AND a commercial fishing community should be very interesting. For example where else could you witness a major oyster shucking contest!! :)
Besides the fair, there are lots of other things to see in St. Mary's County. You might want to start with the county tourist information center, which is not far from the fairgrounds, located at 37575 Charlotte Hall School Road, Charlotte Hall, MD 20622. From there you can find details on other interesting things like Historic St. Mary's City (first capitol of Maryland), Patuxent River Naval Air Museum, Sotterley Plantation, Smith Island cruises, restaruants, fishing opportunities, and on and on. You could easily make a drive to St. Mary's County an enjoyable weekend getaway with lots to do and places to relax.
For information about the St. Mary's County Fair, see this link: