August 2011 Climate Summary

Central Indiana
August 2011
Climate Summary
18th Warmest on record at Indianapolis
11th Driest on record at Indianapolis
The first third of August started out similar to the vast majority of the previous month, which was characterized by above normal temperatures due to a persistent upper level ridge of high pressure. This allowed much of central Indiana to have highs in the upper 80s to mid 90s and lows near 70. On the 8th, the Indianapolis area experienced the 23rd straight day with a high temperature of 90 degrees or higher, which topped the previous string of 19 consecutive days of 90 degrees or higher set back in August of 1936. The upper ridge finally broke down and allowed for the first extended period of below normal temperatures in a long time during the middle part of the month. A series of cold fronts pushed southeastward across the area from the 10th to the 17th and resulted in several multi-day periods where highs dipped into the 70s and low 80s across much of central Indiana.  Lows in the 50s were also a welcomed cool-off.
More frequent variations in temperature occurred over the last 10 days of the month as the upper level ridge stayed positioned to the west over the Rockies and multiple rounds of upper level disturbances tracked southeastward across the region. The 26th to the 30th saw temperatures near or below normal before the month ended with a warm note on the 31st as the 90s returned to the majority of the area.
August 2011 Avg Temp
August 2011 Difference from Normal
Lowest Temperature
96 on 2 and 24
58 on 11
95 on 2
54 on 16
92 on 2
48 on 30
Terre Haute
94 on 24
52 on 11
95 on 2
50 on 30
94 on 2 and 24
49 on 30
Indy – Eagle Crk.
94 on 2
54 on 30
At Indianapolis, 22 days had above normal average temperatures, and 9 days experienced below normal average temperatures.
August 2011 was the 18th warmest in the Indianapolis area since 1871.
The dry rainfall pattern from July continued in many areas through August. Monthly rainfall ranged from a quarter of an inch in portions Sullivan, Knox, and Daviess Counties in southwest Indiana to near 7 inches in Warren, Tippecanoe, Cass and Wabash Counties in north central Indiana.    About one half of the area north of I-74 received normal to above normal rainfall while most areas south of I-74 received much below normal rainfall.   The last time the Indianapolis airport was in a longer and drier period was from July 29 through October 12, 2010.
Abnormally dry to moderate drought conditions continued throughout August in much of central Indiana.   After receiving abundant rainfall in July, portions of southwest Indiana saw virtually no rain in August.  Significant rainfall continued to fall in portions of Tippecanoe County, an area favored with rain this summer.
August 2011 Precipitation
August 2011 Difference from Normal
Wettest Day
Longest Dry Stretch
0.39 on 13
6 days 24-30
1.42 on 8
6 days 24-30
0.93 on 8
3 days 4-6, 10-12, 15-17, 28-30
Terre Haute
0.71 on 23
6 days 24-30
0.53 on 13
5 days 26-30
0.67 on 21
5 days 26-30
Indy – Eagle Crk.
0.85 on 9
6 days 15-20 and 25-30
August 2011 was the 11th driest in the Indianapolis area since weather records began in 1871.
Severe Weather
The most significant severe weather event occurred on the 13th of the month as several lines of scattered thunderstorms pushed southeastward across central Indiana ahead of an approaching cold front. While multiple reports of hail up to 1.75 inches resulted from these storms, the gusty winds were the main impact. Wind gusts over 60 mph brought multiple trees down across the area, and unfortunately caused a stage collapse at the Indiana State Fair Grounds, which tragically resulted in 7 fatalities and over 40 injuries. A review of the severe thunderstorms that occurred on August 13th can be found at
For information on severe weather in other areas during August, visit the Storm Prediction Center “Severe Weather Event Summaries” website at
The maximum wind gust at the Indianapolis International Airport was 58 mph from the west northwest on the 9th due to nearby scattered thunderstorms. Fog or haze was reported at Indianapolis on 14 days this month. Thunder was reported at Indianapolis on 7 days this month.
September 2011 Outlook
The official outlook for September 2011 from the Climate Prediction Center indicates more than a 40 percent chance for below normal temperatures across central Indiana, and nearly an equal chance for below, near, or above normal precipitation. At Indianapolis, the average temperature for the month is 66.9 degrees. The average precipitation for September at Indianapolis is 3.12 inches.  
Data prepared by the Indianapolis Forecast Office.

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