25. Las Vegas, Nevada
> Avg. temperature, Sept. 2021: 86.3 °F
> Change from avg. Sept. temperature, 1901-2000: +5.2
> Hottest September on record: 2018 (Avg temperature: 87.7 °F)
24. Rapid City, South Dakota
> Avg. temperature, Sept. 2021: 65.2 °F
> Change from avg. Sept. temperature, 1901-2000: +5.3
> Hottest September on record: 1998 (Avg temperature: 67.2 °F)
23. Des Moines, Iowa
> Avg. temperature, Sept. 2021: 70.4 °F
> Change from avg. Sept. temperature, 1901-2000: +5.3
> Hottest September on record: 2019 (Avg temperature: 71.6 °F)
22. Milwaukee, Wisconsin
> Avg. temperature, Sept. 2021: 68.3 °F
> Change from avg. Sept. temperature, 1901-2000: +5.3
> Hottest September on record: 2005 (Avg temperature: 69.9 °F)
21. Topeka, Kansas
> Avg. temperature, Sept. 2021: 73.3 °F
> Change from avg. Sept. temperature, 1901-2000: +5.3
> Hottest September on record: 2019 (Avg temperature: 76.2 °F)
