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 Avg Temp

September 2009 Difference from normal



Lowest Temperature




85 on 15

50 on 29, 30




87 on 15

47 on 18, 30 




85 on 15

39 on 30

Terre Haute



84 on 15

39 on 30




83 on 5, 15

41 on 30




85 on 15

43 on 30

Indy – Eagle Crk.



85 on 15

47 on 30


At Indianapolis, there were 5 days with below normal temperatures, 22 days with above normal temperatures, and 3 days with exactly normal temperatures. 


September 2009 was the 44th warmest in the Indianapolis area since 1871.





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.



September 2009 Precipitation

September 2009 Difference from Normal

Wettest Day

Longest Dry Stretch




0.71” on 24-25

13 days   7-19




0.14” on 24

12 days   9-20




0.49” on 20-21

10 days 10-19

Terre Haute



0.15” on 24

13 days   7-19 




0.96” on 24-25

11 days   9-19




0.98” on 24-25

12 days   8-19

Indy – Eagle Crk.



0.48” on 24

13 days   7-19


September 2009 tied for the 38th driest in the Indianapolis area since 1871.


Severe Weather

September was mostly a quiet weather month in central and much of southern Indiana.  Windy conditions existed for about a day in much of the region following the passage of a strong cold front on the 27th.  The Indianapolis Weather Office did not receive any reports of damaging winds, hail or flash flooding.


For information on severe weather in other areas during September, visit the Storm Prediction Center “Severe Weather Event Summaries” website at http://www.spc.noaa.gov/climo/online/



At the Indianapolis International Airport, the peak wind gust this month was 47 mph from the west northwest on September 28.  Thunder was reported on 4 days. Fog or haze was observed on 17 days, with 2 days of dense fog observed.


October 2009 Outlook

The official outlook for October 2009, from the Climate Prediction Center, indicates an equal chance of above, below, or near normal temperatures and precipitation across Central Indiana.


Data prepared by Indianapolis Forecast Office.


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