July 2011 Climate Summary - Record Breaking!

Central Indiana
July 2011
Climate Summary
*Driest on record at Indianapolis*
2nd Warmest on record at Indianapolis
July 2011 will go down in history at Indianapolis as the hottest month in 75 years since July of 1936 and the 2nd hottest since weather records began in 1871. During the summer of 1936, the Midwest and much of the nation was in the middle of the epic Dust Bowl. A persistent upper level ridge of high pressure is to blame for the prolonged period of heat this July. Nearly every day of the month was at or above normal. Much of the second half of the month was near 10 degrees above normal, when the most intense heat waves impacted the area. Combined with relatively high amounts of moisture in the air, conditions became dangerous and posed a clear threat for those exposed to the excessive heat.  Heat index values consistently ranged from the 100s to 110s across central Indiana during several periods in the second half of the month.
Several locations broke into the triple digits on the 21st. Indianapolis reached 100 on this day, which was the first time since August of 1988 (102 degrees). Many locations had impressive strings of consecutive days with maximum temperatures at least 90 degrees. Shelbyville and Eagle Creek both finished the month with 16 straight days of highs at or above 90 degrees, and Indianapolis had 15. Temperatures look to continue such a trend into early August, which would give Indianapolis a good chance of coming close to the record of 19 straight days set back in August of 1936.
July 2011 Avg Temp
July 2011 Difference from Normal
Lowest Temperature
100 on 21
63 on 5
101 on 21
59 on 5
97 on 21
57 on 14
Terre Haute
99 on 21
60 on 5
96 on 21
59 on 15
97 on 21 and 20
60 on 14
Indy – Eagle Crk.
98 on 21
63 on 14
At Indianapolis, all 31 days had above normal average temperatures.
July 2011 was the 2nd warmest in the Indianapolis area since 1871.

The persistent upper ridge of high pressure that prevailed over the central United States for the vast majority of the month not only contributed to above normal temperatures, but it has also deflected storms from much of central Indiana. Any chances for precipitation usually accompanied a weak frontal passage or stationary front, and any development typically was not widespread across the area. With generally weak wind shear in place, there were not many opportunities for storms to become well-organized or longer-lived. As a result of the lack of widespread shower and thunderstorm development, the monthly total precipitation across central Indiana included some notable variation. While most locations were below normal, including much of the central and eastern portions having less than half an inch, some areas to the west and southwest had 5 to 8 inches.
July 2011 Precipitation
July 2011 Difference from Normal
Wettest Day
Longest Dry Stretch
0.22 on 24
15 days 9-23
2.01 on 2
10 days 13-22
1.07 on 7
10 days 12-21
Terre Haute
1.36 on 29
6 days 13-18
1.46 on 3
15 days 9-23
0.03 on 8
7 days 9-15
Indy – Eagle Crk.
0.23 on 30
12 days 12-23
July 2011 was the driest in the Indianapolis area since weather records began in 1871.


Severe Weather

July proved to be quite inactive with severe weather, as there were only a few occurrences during the entire month. While storm development on the 2nd and 20th resulted in isolated hail and wind damage including some downed trees, the most significant event occurred on the 11th. During the evening of the 11th, a line of scattered thunderstorms developed along a stationary front draped across the northern portion of central Indiana. The storms caused multiple downed trees and power lines along with hail up to 1.75 inches in diameter across some of the northern counties.
For information on severe weather in other areas during July, visit the Storm Prediction Center “Severe Weather Event Summaries” website at http://www.spc.noaa.gov/climo/online/.
The maximum wind gust at the Indianapolis International Airport was 48 mph from the south on the 3rd due to nearby scattered thunderstorms. Fog or haze was reported at Indianapolis on 19 days this month. Thunder was reported at Indianapolis on 4 days this month.
August 2011 Outlook
The official outlook for August 2011 from the Climate Prediction Center indicates an equal chance for above normal, normal, or below normal temperatures and precipitation across central Indiana.   At Indianapolis, the average temperature for the month is 74.2 degrees. The average precipitation for August at Indianapolis is 3.13”.  
Data prepared by the Indianapolis Forecast Office.

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