August 2009 Climate Summary

August 2009 was an active weather month. Severe weather, flash flooding, river flooding, dry spells, summer warmth and cool spells were all part of the weather during August. August monthly temperatures averaged below normal, but not nearly as cool as July.  Monthly precipitation departures were split nearly down the middle. About half of the area received normal to above normal rainfall and the other half received below normal rainfall.
Temperatures during August 2009 rebounded from the record to near record cool July weather.   Average monthly temperatures during August were 1 to 2 degrees warmer than in July. Normally the average monthly temperature declines nearly 2 degrees from July to August.
The cool weather pattern similar to July lingered over central Indiana for portions of August. August monthly temperatures averaged slightly below normal to 3 degrees below normal.   August began on the cool side and warmed up by August 8 with the return of summer heat. Seasonable to above normal temperatures continued through August 21. During this period, temperatures reached the low 90s in much of central Indiana. After, a short cool spell from August 22-24, seasonable temperatures returned again from August 25-28.  August ended on a very cool note. No temperature records were set at Indianapolis this month.
August 2009 Avg Temp
August 2009 Difference from normal
Lowest Temperature
90 on 9, 16, 17
51 on 30
93 on 9, 16
45 on 31
91 on 9, 16
44 on 31
Terre Haute
91 on 9
50 on 30, 31
89 on 16
48 on 31
88 on 16
47 on 31
Indy – Eagle Crk.
90 on 16
51 on 31
At Indianapolis, there were 15 days with below normal temperatures, 15 days with above normal temperatures, and 1 day with exactly normal temperatures.
August 2009 tied as the 51st coolest in the Indianapolis area since 1871.
August 2009 was a rather dry month for much of southwest Indiana and portions of east central Indiana. The remainder of central and southern Indiana was normal or on the wet side.  The wettest area was southeast Indiana…where a few locations received over 10 inches of rain. The driest areas were in southwest Indiana.  A few locations received less than one half inch of rain.   About 60 % of central and southern Indiana received 2 to 5 inches of rain during August.
The largest rain for August, in much of central Indiana, occurred on August 4.  Portions of central and southeast Indiana received 3 to nearly 8 inches of rain. The Indianapolis International Airport set a daily rainfall record with 3.81 inches. This is the typical amount of rain the Indianapolis International Airport receives for the entire month of August.
The ensuing river flood along the East Fork White River from Columbus in Bartholomew County to Bedford  in Lawrence County was the highest ever for the month of August. The river flood along the East Fork White River from Williams Dam in Lawrence County to Petersburg in Pike County was the highest for the month of August since 1979.
After August 4 little rain fell in central Indiana until August 17. From August 17-20 much of central Indiana received 1 to 3 inches of rain. This rain alleviated the dry conditions that existed in many areas north of Interstate 70.
August 2009 Precipitation
August 2009 Difference from Normal
Wettest Day
Longest Dry Stretch
3.81” on 4

13 days:  

1.23” on 19-20
11 days:  
1.54” on 19-20
 6 days:   
Terre Haute
1.96” on 19-20
 6 days:  
 6 days: 
1.85” on 4
 6 days: 
 6 days: 
2.86” on 4
13 days:   
Indy – Eagle Crk.
3.77” on 4
 9 days:   
August 2009 ranked as the 27th wettest in the Indianapolis area since 1871.
As an interesting note, the months of April, May, June, July and August have brought a combined rainfall to Indianapolis of 30.06 inches. This is the 3rd wettest combined April through August since 1871 and the wettest since 1957.
Severe Weather

Severe storms from early morning through mid afternoon on August 4 brought a tornado, damaging winds, hail, copious rainfall and flash flooding to central Indiana. National Weather Service teams determined a weak EF1 tornado struck Eminence and winds in excess of 60 mph occurred over a large portion of northern Brown County. Flash flooding in portions of Morgan, Johnson, Shelby, and Bartholomew counties resembled conditions of June 2008. Severe flash flooding occurred in Decatur, Jennings and northern Jackson counties. For a more detailed review of the events of August 4 go to on the web.
For information on other storm reports of severe weather in August, visit the Storm Prediction Center “Severe Weather Event Summaries” website at

At the Indianapolis International Airport:

The peak wind gust this month was 67 mph from the west on August 4. Thunder was reported on 5 days. Fog or haze was observed on 14 days, with 2 days of dense fog observed.

September 2009 Outlook
The official outlook for September 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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