The year 2011 was the wettest the region has ever seen, with September setting records as the wettest since record-keeping began in 1895, according to the National Weather Service at State College.
On Oct. 16, 11 inches of rain fell at Williamsport, increasing the annual total to 61.3 inches and breaking the previous annual precipitation record of 61.27 inches set in 1972.
As of Tuesday, the precipitation total stood at 70.2 inches for the year, more than 10 inches beyond the 1972 record.
In comparison, the region saw only 21.98 inches of precipitation by this time last year, the service said.
According to a Penn State University study, September 2011 was the wettest September in Pennsylvania since 1895, topping the previous record set in 2004 by more than an inch.
According to the study, the state's average rainfall was 10.20 inches in September or 252 percent of normal.
The rainfall total in the Middle Susquehanna division, which includes Williamsport, topped the previous record of 10.64 inches set in 1999 by 7.30 inches, according to the study.
On Sept. 8, the ground was already saturated from abundant rainfall in August when a stalled front and the remnants of Tropical Storm Lee moved into eastern Pennsylvania, continuing to drop heavy rain. Williamsport reported more than an inch of rainfall in one day, establishing a daily maximum rainfall recorded. The last record of .96 inches was set in 1916.
According to the National Weather Service, on Sept. 8, nearly 9 inches of rain fell at the Williamsport Regional Airport, nearly 8 inches fell in the city, just shy of 6.5 inches fell at the Tioga-Hammond dam in Tioga County, and just shy of 4.5 inches fell in Wellsboro.
Several other heavy rain events left portions of the state with more than a month's worth of rain by Sept. 10, according to the Penn State study.
Rainfall totals during the next two weeks were relatively light, then another 3-plus inches were added to the monthly totals when a cutoff low over the Midwest during the last week of September steered storms laden with moisture into the Northeast.
New daily, monthly, and multi-month records were set.
The Middle Susquehanna climate division, which averaged almost 18 inches, was home to the station with the greatest monthly total - Bear Gap, with 25.3 inches.
A narrow band from northern York County to the New York border saw at least 10 inches of rain from Sept. 5 through Sept. 9.
Spring rainfall also set records, according to the study. May was the fourth consecutive month with above normal precipitation totals.
It was the wettest May since 1990 and the 10th wettest May since 1895.
The state average was 5.79 inches, which was 142 percent of normal.
So far, 2011 has been the wettest January through May period, the wettest February through May and the wettest March through May in Pennsylvania's 117 years of record-keeping.
Departures ranged from 107 percent in the East Central Mountains to 202 percent of normal in the Upper Susquehanna division. Six climate divisions ranked in the top 17 wettest since 1895 including the Upper Susquehanna. which ranked third. and the Middle Susquehanna. which ranked fifth.