July 2012 - The Hottest Month on Record at Indianapolis

Central Indiana
July 2012
Climate Summary
Warmest July on record at Indianapolis
Tied for 6thDriest July on record at Indianapolis
The hot, record breaking summer continued into July across central Indiana as an upper level ridge dominated much of the central US and the Ohio Valley for large stretches of the month. The worsening drought conditions across Indiana further contributed to warmer temperatures that exceeded 90 degrees on 28 days during the month at Indianapolis, and 95 degrees a whopping 19 times. Even more impressive was that the mercury reached 100 degrees on seven days at Indianapolis. This led to not only the warmest July on record, but the hottest month in recorded history at Indianapolis with an average temperature of a whopping 84.0 degrees. At other locations across central Indiana, Terre Haute led the way with an amazing 12 days at or above 100 degrees, with both Bloomington and Lafayette matching Indianapolis with 7 days at or above the century mark.
The hottest stretch of the month for central Indiana commenced on Indepedence Day as temperatures surged into the lower 100s, providing many locations with one of the warmest 4th of Julys on record. This began a string of four days with temperatures topping out above the century mark, highlighted on the 6th and 7th by highs that reached 105 and 106 degrees in many locations. In Indianapolis, the official high of 105 on both the 6th and 7th came within one degree of tying the all-time record high of 106 degrees, set on July 22, 1901, July 21, 1934, and July 14, 1936. Temperatures topped out above the century mark a few more times between the 17th and 25th across central Indiana.
Temperatures remained warm at night too, as overnight lows remained above 70 degrees for long stretches throughout the month. Indianapolis experienced a low temperature of 81 degrees on the 7th, marking the first time the low had stayed above 80 degrees at Indianapolis since August 22, 1936. Indianapolis never saw the temperature drop below 70 degrees at night until the morning of the 20th. With the exception of lows of 61 degrees on the 21st and 62 degrees on the 29th, temperatures did not drop any lower than 68 degrees throughout the month.
Below is a list of temperature records for Indianapolis reached, with old records following in parenthesis, during what will remembered as a historic month for heat not just in Indianapolis but throughout central Indiana.
  • Hottest Month on Record – 84.0 Degree Avg Temp (82.8 – July 1936)
  • Hottest Max Temp Avg on Record – 95.6 Degree Avg Temp (93.7 – July 1936)
  • Number of 90-Degree Days in a Month – 28 Days (25 Days – July 1901)
  • Number of 95-Degree Days in a Month – 19 Days (16 Days – July 1936)
  • Consecutive Days with Lows at or Above 70 Degrees – 22 Days: June 28-July 19 (20 Days: June 26-July 15, 1921)
As we transition into the second half of the summer, there could be more records that fall. Here is where this year stands so far on several important temperature records at Indianapolis:
  • Number of 90-Degree Days in a Year – 43 in 2012 (Record: 58 Days in 1983)
  • Number of 95-Degree Days in a Year – 22 in 2012 (Record: 31 Days in 1936)
  • Number of 100-Degree Days in a Year – 9 in 2012 (Record: 12 Days in 1936)
  • Average Annual Temperature through July – 58.7 Degrees in 2012 (warmest on record through July 31)
  • Average Summer Season (June-August) Temperature through July – 79.4 Degrees in 2012 (3rd warmest on record through July 31)
  • Average Annual Maximum Temperature through July – 69.0 Degrees in 2012 (warmest on record through July 31)
  • Average Summer Maximum Temperature through July – 91.1 Degrees through 2012 (warmest on record through July 31)
  • Average Annual Minimum Temperature through July – 48.4 Degrees in 2012 (tied for 2nd warmest on record through July 31)
July 2012      Avg Temp
July 2012 Difference from Normal
Lowest Temperature
105 on 6 and 7
61 on 21
103 on 7
55 on 29
101 on 6
56 on 21
Terre Haute
106 on 6 and 7
56 on 29
106 on 7
55 on 21
105 on 6 and 7
57 on 21
Indy – Eagle Crk.
102 on 7 and 25
61 on 29
          At Indianapolis, all 31 days experienced above normal average temperatures.
July 2012 was the warmest in the Indianapolis area since 1871.

July was among the driest months of record in portions of central and southwest Indiana to one of the wettest in isolated areas of south central Indiana. Monthly rainfall totaled from around one-quarter of an inch in portions of Boone … Putnam and Hendricks Counties in central Indiana to nearly 10 inches in portions of Crawford County in extreme south central Indiana.
The wetter areas of the state included northern and central Indiana north of a line from Chicago to Cincinnati and south central Indiana.   These locations received mostly 2 to 5 inches of rainfall during July. The remainder of Indiana measured generally 1 to 2 inches. Normal rainfall for July is 3 to 5 inches. Rainfall during the first half of July was much more scattered that during the second half of July.
Measurable rainfall did not occur at the Indianapolis airport until the 18th.   This marked the driest start ever to the month of July for the Indianapolis area and driest 47-day period of record with only 0.09 inches of rainfall. The combined precipitation of 0.92 inches that fell at Indianapolis during the months of June and July, set a new record for the driest June and July, shattering the old mark of 2.45 inches that fell in June and July 1930.
Drought conditions expanded during July. The U.S. Drought Monitor on July 17th indicated nearly 90% of the state in severe to extreme drought. The following week the U.S. Drought Monitor indicated nearly 20% of the state was in the exceptional drought.   Burning bans were noted for nearly all Indiana counties. As July drew to a close, drought conditions improved in portions of extreme northern, south central and southeast Indiana with little change in the exceptional drought areas of central and southwest Indiana. Click on the links below for more information about the worsening drought conditions across Indiana.
Streamflow in much of central and southern Indiana remained at seasonally record or to near record low levels for the entire month of July. Water sources were a concern for livestock operations as many creeks and ponds dried up during the month. Crop yields in much of the state will be reduced because of the drought. Numerous wildfires broke out during July, very unusual for July in Indiana. The state of Indiana requested voluntary water reductions in all areas. Mandatory water restrictions on outdoor watering remained in place in the City of Indianapolis and many nearby metropolitan areas.
Rainfall deficits throughout the growing season have steadily increased as severe to exceptional drought conditions have expanded across the entire state of Indiana. For more information about the rainfall deficits experienced since April 1 at several stations in central Indiana, click on the link below.
July 2012 Precipitation
July 2012 Difference from Normal
Wettest Day
Longest Stretch Without Measureable Precipitation
0.40 on 18
 17 days 1-17
0.70 on 19
 8 days 9-16
1.19 on 14
 12 days 2-13
Terre Haute
0.35 on 14
 7 days 19-25
0.36 on 7
 7 days 20-26
0.51 on 19
 17 days 1-17
Indy – Eagle Crk.
0.23 on 27
 7 days 1-7 and 20-26
July 2012 was the 6th driest in the Indianapolis area since weather records began in 1871.
*Data missing for Lafayette on July 1.
Severe Weather
Localized strong to severe thunderstorms occurred on several days throughout the month. The events that impacted the largest portions of central Indiana took place on the afternoon of the 8th, the afternoon and evening of the 19th, the morning of the 24th, and the afternoon and evening of the 27th. Damaging wind gusts were most common from these storms, with some reports of large hail as well. The thunderstorms often provided generous and much needed rainfall as well.
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 Indianapolis International Airport was 48 mph out of the southwest on the 18th as thunderstorms moved through the Indianapolis area. Fog or haze was reported at Indianapolis on 5 days during the month. Thunder was reported on 5 days during the month.
August 2012 Outlook
The official outlook for August 2012 from the Climate Prediction Center indicates a much higher chance of above normal temperatures for central Indiana.  At Indianapolis, the average temperature for the month is 74.2 degrees. The outlook also calls for a greater chance of below normal precipitation. The average precipitation for August at Indianapolis is 3.13”.
Data prepared by the Indianapolis Forecast Office.

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