September 2019 was Indy’s warmest September on record

September this year at the Indianapolis International Airport was the warmest September on record, based on data from the NOAA Regional Climate Center. Records for the Indy airport go back to 1943.

Thermometer 13925024415866The mean average temperature for September this year was 73.7 degrees Fahrenheit. That’s 2 degrees warmer than the  next-warmest September on record, which came in 2007. It’s about 7 degrees warmer than the mean  of all September averages since 1943, which is 66.9 degrees.

Last year’s September (2018)  ranked 4th warmest since 1943.

Records for Monroe County’s airport go back just a couple of decades. This year’s September numbers are the warmest since 1998 by about a degree—72.1 compared to 71 degrees last year.

Data in the climate center’s database for Indiana University station’s in Bloomington go back to 1896, but temperature data stopped getting reported in late August this year. The Beacon has made some inquiries into that. [Updated Oct. 4, 2019: The word from National Weather Service is: “The IUBloomington station is undergoing some construction so the site is temporarily down. The time table for it being back up and running is unknown due to the construction. But, it will be back.”]

Not counting this year, the warmest September on record for Bloomington came in 1933 with a monthly mean average temperature of 74.5 degrees. If the airport temperature were taken as a proxy for the IU station, this year’s 72.1 degrees would rank as the 10th warmest September since 1896.

Swapping in Monroe County airport numbers would be a tricky business—the monthly averages can differ by as much as 3 degrees compared to the IU station.

Here’s the table of monthly averages extracted from the NOAA data sorted highest-to-lowest by the month of September.

Monthly Mean Avg Temperature for INDIANAPOLIS INTL AP, IN

YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
2019 27.4 33.8 38.2 54.1 64.2 71.2 78.2 74.7 73.7 M M M
2007 32.5 19.7 49.0 50.8 68.1 74.2 74.3 79.9 71.7 62.1 43.4 34.1
1998 36.6 40.8 42.0 53.2 67.0 71.4 74.9 75.3 71.4 57.0 45.5 36.5
2018 25.1 37.7 38.9 47.1 72.6 75.5 77.0 75.9 71.3 55.9 37.8 36.5
2016 28.9 34.8 49.2 53.7 62.3 74.5 76.5 78.2 71.3 60.7 48.1 30.3
2002 35.1 35.6 40.1 54.8 59.7 73.8 78.3 77.4 71.3 53.3 40.3 33.0
1961 23.6 34.0 43.6 45.6 56.4 67.9 73.4 71.4 70.9 56.2 42.0 29.0
2015 25.3 20.2 39.2 54.5 66.8 72.6 74.6 72.9 70.5 57.0 48.0 42.6
2010 24.6 26.0 45.9 59.6 66.0 76.0 78.7 79.5 70.5 58.1 44.8 25.4
2005 30.7 36.3 38.3 55.0 60.1 74.8 76.4 76.6 70.5 56.3 44.5 27.1
1978 18.2 17.8 36.7 55.2 63.5 74.0 77.1 74.9 70.3 52.6 45.7 34.3
2008 28.6 29.8 40.4 53.8 59.8 73.2 75.0 73.8 70.1 56.0 41.6 30.7
2017 34.9 43.3 43.8 59.3 62.3 72.1 76.2 73.0 69.8 58.2 43.9 30.2
1986 28.5 31.3 43.9 53.7 63.4 72.8 77.5 70.1 69.8 55.5 39.7 32.3
1973 30.7 31.4 49.4 51.3 59.5 73.2 76.0 74.4 69.8 59.4 46.4 30.8
1960 31.8 28.1 26.2 54.8 58.8 68.4 71.6 74.1 69.8 54.7 42.3 24.5
1977 10.2 28.1 46.5 57.1 70.6 71.2 77.9 74.0 69.6 54.2 45.9 29.2
1954 30.8 40.0 37.6 57.4 57.9 75.5 77.8 73.5 69.6 55.9 42.0 32.2
2013 29.9 30.9 35.5 52.5 65.4 72.0 73.9 74.9 69.5 54.6 39.2 29.9
1983 30.5 35.5 42.9 48.2 58.2 71.8 79.7 80.1 69.4 57.4 44.1 20.1
1971 23.4 28.8 37.3 51.0 58.9 75.6 72.2 71.2 69.4 62.0 43.1 38.4
1970 17.9 28.6 38.0 55.1 65.6 71.4 75.2 74.2 69.1 55.1 40.9 34.7
2004 25.2 32.1 45.4 54.9 66.9 70.9 73.0 69.8 69.0 55.9 46.8 31.8
1955 27.4 32.2 40.6 57.1 63.6 67.1 79.4 75.9 68.9 54.7 37.5 28.6
2009 23.0 33.9 47.2 53.9 63.6 73.4 70.9 73.0 68.5 51.6 47.4 31.1
1959 24.9 31.6 38.8 51.7 65.7 73.0 75.2 77.3 68.4 53.8 35.5 35.9
1972 26.5 28.4 39.8 52.1 65.0 68.8 74.6 73.1 68.3 51.5 39.9 31.9
1987 27.6 35.4 44.5 52.5 68.1 73.6 75.7 73.6 68.1 48.5 46.3 35.8
1980 28.5 22.5 36.0 49.1 64.0 69.1 78.5 76.6 67.9 50.9 40.3 31.8
1991 26.9 35.3 43.7 55.3 68.3 74.6 76.6 75.2 67.8 57.5 40.1 35.7
1965 27.5 29.5 33.7 54.4 68.3 71.7 72.9 71.1 67.5 53.7 44.7 38.6
1945 22.8 31.9 51.1 52.6 56.4 68.1 72.4 72.1 67.5 52.1 42.2 23.9
1948 21.0 31.2 41.1 54.0 60.7 71.3 74.5 73.6 67.4 51.2 44.7 34.3
1988 25.9 27.2 41.4 51.9 64.3 73.4 78.3 77.5 67.3 48.1 44.2 31.7
1964 30.7 29.0 40.5 54.7 65.6 73.3 74.6 72.5 67.2 51.7 45.3 32.2
1953 32.8 35.6 42.1 47.6 64.6 75.9 75.9 74.3 67.2 58.3 43.6 32.8
1999 28.4 37.4 38.4 54.9 64.3 73.7 79.2 72.3 67.1 55.2 48.8 34.6
1990 37.3 37.6 46.2 51.4 60.1 71.3 73.9 72.5 66.9 53.9 47.5 34.6
1994 21.8 29.6 40.9 54.1 60.3 74.9 75.5 71.8 66.4 57.0 48.6 38.8
1947 33.7 22.5 32.9 50.6 58.3 68.1 70.6 79.0 66.4 62.4 37.9 31.7
1946 29.0 33.0 51.9 53.0 59.2 70.5 74.7 69.0 66.3 59.0 45.2 35.5
1985 20.4 26.0 44.6 57.1 64.9 70.6 74.3 71.2 66.2 57.6 46.6 22.4
1997 24.3 35.9 42.9 48.3 56.7 69.6 75.3 71.6 66.1 54.6 39.0 33.4
2011 23.8 33.4 43.6 55.8 63.8 73.7 82.0 76.9 66.0 55.7 48.7 37.8
1952 33.1 35.3 39.8 52.0 61.1 76.6 76.7 72.9 66.0 49.8 42.9 34.8
1944 32.6 33.0 36.8 49.7 67.5 74.0 75.8 74.1 66.0 54.1 43.0 25.3
1967 32.6 27.7 43.9 53.6 59.3 73.9 73.8 71.1 65.9 55.2 39.4 33.7
1968 25.1 26.4 42.8 53.7 58.6 72.3 75.3 74.4 65.8 54.4 42.9 30.6
1996 25.1 31.2 35.5 49.3 61.9 72.1 73.1 74.9 65.5 55.3 37.2 34.4
2014 20.1 22.3 35.7 53.0 63.1 72.7 70.1 73.8 65.4 54.2 35.9 33.3
1963 19.5 21.1 42.4 53.3 59.7 71.3 73.3 68.9 65.4 62.0 45.0 18.5
1958 28.0 23.7 35.9 52.1 61.3 66.8 73.5 71.9 65.4 54.9 43.6 24.2
2012 33.7 37.3 56.6 54.5 68.8 74.6 84.0 74.9 65.2 52.7 41.4 38.4
2000 27.9 38.7 47.0 51.4 64.9 71.0 73.0 73.6 65.2 57.7 40.6 19.7
1966 22.4 30.4 43.3 51.3 58.4 72.3 79.2 73.1 65.2 51.9 43.8 32.7
2001 28.0 34.6 38.4 58.5 64.4 70.2 74.4 75.4 65.1 54.3 49.5 38.1
1992 31.5 38.4 43.2 52.1 60.5 68.1 73.5 69.4 65.1 53.4 43.2 33.3
1969 25.7 31.6 35.6 54.0 63.4 69.8 75.8 72.6 65.1 53.8 37.5 28.1
1979 17.9 18.8 43.3 49.8 61.1 71.1 72.9 72.3 64.9 53.1 41.3 34.8
1995 28.6 30.0 45.0 51.9 61.6 72.8 76.6 79.6 64.7 55.7 37.0 28.5
2003 21.6 25.4 43.3 54.6 61.0 68.2 74.0 74.9 64.6 54.4 47.2 34.4
1981 23.4 33.0 39.9 57.3 59.9 73.2 75.4 72.8 64.6 53.1 44.2 27.7
1957 23.5 36.5 40.8 53.3 62.1 72.1 75.4 73.3 64.6 51.3 40.7 36.2
1950 37.3 31.6 36.7 45.9 63.6 68.6 72.2 70.2 64.6 59.2 36.4 23.4
1989 36.3 27.2 42.5 51.4 59.3 71.4 75.7 71.8 64.4 55.3 40.9 18.7
1982 20.1 26.4 42.5 48.6 68.6 67.8 76.2 71.7 64.4 55.7 44.2 40.2
1984 22.7 37.3 32.9 50.0 58.7 75.3 72.4 74.2 64.2 61.3 43.0 38.8
2006 39.7 32.3 41.7 57.1 61.3 70.4 76.6 75.0 64.1 52.0 45.5 38.7
1956 27.2 33.5 40.2 48.9 62.5 72.1 72.9 73.0 63.8 60.7 41.1 38.7
1976 23.9 38.8 46.6 53.4 58.8 71.3 73.9 71.2 63.5 48.7 34.6 24.5
1975 32.0 32.0 36.8 48.8 65.5 71.5 73.5 76.1 62.6 55.9 46.4 32.8
1962 23.7 30.6 37.7 51.1 69.1 73.2 73.3 72.4 62.6 56.7 42.3 25.4
1951 29.1 30.6 37.8 48.3 63.8 69.9 74.1 72.0 62.6 57.0 35.6 30.6
1993 31.6 27.4 39.1 50.7 63.4 70.9 77.2 75.3 62.1 51.6 42.2 32.4
1943 28.2 31.7 35.8 47.7 61.1 74.9 75.9 74.5 61.9 53.5 37.9 28.5
1974 31.6 32.4 45.2 55.0 62.0 68.6 75.9 71.8 60.6 52.5 42.4 32.9
1949 34.0 35.0 41.0 50.2 63.1 73.4 78.3 73.8 60.6 59.1 42.3 35.8

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