7th Warmest September on Record

7th Warmest September on Record at Indianapolis


A pattern of above normal temperatures continued across central Indiana during September as the month turned out to be the 7th warmest September on record at Indianapolis since temperature records started in 1871. This was the warmest September since 1941.

The average monthly temperature of 71.7 degrees was 5.4 degrees above normal. There were 22 days in September when the daily average temperature was above normal.

The warmest September on record was in 1933 with an average monthly temperature of 73.2 degrees. The coolest September on record at Indianapolis occurred in 1918 when the average monthly temperature was only 59.8 degrees.

At the Indianapolis International Airport the temperature was 90 degrees or higher on 5 days during September. Normally only 2 days in September would reach 90 or higher. This was the most for September since 2002. The highest temperature in September 2007 was 96 on the 5th.  This was the warmest temperature for September since 1991 when 96 was also observed.  The lowest temperature was 43 on the 15th.  September 1999 was the last time the temperature fell to 43 degrees earlier in the late summer season.

On September 23rd the high of 90 tied the record previously set in 1891, 1941, and 1961. The next day, September 24th, a record high was set with a high of 92 degrees. This surpassed the previous mark of 91 set in 1891. This was the warmest temperature so late in the year since 1998. The 92 degree mark has been reached only 4 times since 1871 on September 24th or later.


Total September precipitation at the Indianapolis Airport was 1.59 inches which was 1.29 inches below normal. Nearly all of the monthly precipitation occurred from the 7th through the 9th, and on the 25th.

The wettest September on record at Indianapolis was in 2003 with a total of 10.37 inches. This was largely due to the 7.20 inches of rain on the 1st of September that year. This value of 7.20 inches stands as the maximum rainfall at Indianapolis for any calendar day on record.

This September was the driest since 2004 and was the 6th month in a row at Indianapolis with below normal precipitation. There were only 6 days with measurable precipitation at the airport, with a trace recorded on 2 days. No measurable precipitation was recorded during a 2 week period from the 10th through the 24th at Indianapolis. The driest September on record was in 1963 when only 0.24 of an inch was recorded.

Other Notable Features

The peak wind in September was a 40 mile per hour gust from the southwest during a thunderstorm in the late afternoon of the 25th. A thunderstorm was observed at the airport on 3 days. Sunshine for the month was 73 percent of possible.

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