 Normal yearly precipitation based on the 30-year average from 1981–2010 is , falling on an average 133 days.Monthly precipitation has ranged from in June 1972 (due to heavy rainfall from Hurricane Agnes) to in September 1943, while for annual precipitation the historical range is in 2011 to in 1930.Williamsport is the larger principal city of the Williamsport-Lock Haven CSA, a Combined Statistical Area that includes the Williamsport metropolitan area (Lycoming County) and the Lock Haven micropolitan area (Clinton County), which had a combined population of 157,958 at the 2000 census.