The month of September has turned out to be drier than normal. Locally, I've collected 2.29" of rain which is 0.59" below normal. Temperatures have also been below normal by 0.7F. The warmest temperature in September was 82F on the 15th and the lowest was 43F on the 30th. Below is a much more detailed look at September for Central Indiana.
From the NWS in Indianapolis, Indiana
Central Indiana September 2009 Climate Summary
September 2009 was a quiet weather month. A persistent High Pressure Area with northerly or easterly winds dominated the weather from the 1st through the 19th. As the High Pressure Area moved east, an upper level trough remained over the state from the 20th through the 27th bringing wet weather to southern Indiana. September finished with autumn like weather after a strong cold front moved through the area late on the 27th.
September monthly temperatures averaged from slightly below normal to more than 2 degrees above normal. Little rain fell in many areas north of I-70 while in southern Indiana rainfall exceeded 6 inches in numerous areas near US 50 and south.
Monthly temperatures during September 2009 averaged from slightly more than 1 degree below normal in west central Indiana to more than 2½ degrees above normal in some areas of central Indiana. Compared to August, average temperatures declined 3.5 to 5.5 degrees. Typically temperatures fall more than 7 degrees from August to September.
September began on the cool side and ended on the cool side. From the 3rd through the 28th, temperatures ranged from near normal to above normal. Summer like weather prevailed from the 7th through the 23rd as temperatures reached into the upper 70s and lower 80s under generally sunny skies. The warmest day was the 15th when temperature rose into the middle 80s across the region. The coolest temperatures occurred on the 30th when temperatures fell to the 40s in most areas. No temperature records were set at Indianapolis this month.
September 2009 was a very dry month for much of central Indiana along and north of I-70 and a very wet month for southern Indiana near and south of US Highway 50. Rainfall was generally normal to much above normal south of a line from Graysville, Indiana to Spencer, Indiana to Brookville, Indiana and much below normal north of I-70.
Monthly rainfall ranged from less than a third of an inch in the Lafayette area to more than 10 inches in extreme southeast Jackson county and southwest Jennings county. Other southern Indiana areas near the Ohio River also received over 10 inches of rain.
There were two rain events during September, the 6th and the period from the 19th through the 26th. The heaviest rain was concentrated in southern Indiana for both times. Little or no rain fell from the 7th through much of the 19th in central and southern Indiana. Because of the warm and dry weather between these rain events, river flooding did not develop along the East Fork White or White Rivers from the heavy rains in the later part of the month. Dry to abnormally dry conditions prevailed during September for the area along and north of I-70.