Monthly Attribution Overview - September 2024

The report finds that September 2024 was unusually warm across much of the U.S., with 171 of 191 analyzed cities experiencing warmer-than-normal temperatures. While the highest temperature anomalies occurred in the Midwest and northern Great Plains, the strongest climate change signals (CSI values) were concentrated in the Southwest and Florida.

• September 2024 temperature anomalies were elevated across most of the U.S., with 171 out of 191 analyzed cities being warmer than normal. The most significant anomalies were located in the Midwest and northern Great Plains, where average temperatures in the Northern Rockies and Plains were 5.4 °F above normal and 4.3 °F above normal in the Upper Midwest.
• Twelve cities experienced their hottest September on record, including Phoenix, Minneapolis, and Denver, while another 26 cities saw temperatures in their top 5 hottest Septembers.
• Rapid City, South Dakota, recorded the highest temperature anomaly of 8.70°F. Long-term trends show that 189 of 191 analyzed stations have positive September temperature trends since 1970, with Reno, NV, being the fastest-warming station, increasing by 10.6 °F on average.
• The Climate Shift Index (CSI) identified the strongest climate change influence in the Southwest and Florida. Cities in the Southwest averaged at least 10 days with CSI values of 3 or higher (meaning temperatures were at least 3x more likely due to climate change), which is more than double the average of any region except the Southeast (6 days).
• San Juan, Puerto Rico, showed the strongest climate signal with 30 days at CSI 5, indicating temperatures were at least 5 times more likely to occur because of climate change. In Florida, five of the top 10 cities with the strongest climate signals (Miami, West Palm Beach, Fort Myers, Sarasota, and Tampa) each had at least 9 days with CSI values of 5.

APA

Climate Central (2024). Monthly Attribution Overview - September 2024. https://assets.ctfassets.net/cxgxgstp8r5d/61YskkL2WJimzoZ27rXdCT/ce65f863efe46046228f4d713da953e1/Climate_Central___September_2024_U.S._Attribution_Report.pdf

Chicago

Climate Central. Monthly Attribution Overview - September 2024. 2024. https://assets.ctfassets.net/cxgxgstp8r5d/61YskkL2WJimzoZ27rXdCT/ce65f863efe46046228f4d713da953e1/Climate_Central___September_2024_U.S._Attribution_Report.pdf.

Wikipedia

{{cite report |author=Climate Central |title=Monthly Attribution Overview - September 2024 |date=September 2024 |url=https://assets.ctfassets.net/cxgxgstp8r5d/61YskkL2WJimzoZ27rXdCT/ce65f863efe46046228f4d713da953e1/Climate_Central___September_2024_U.S._Attribution_Report.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{climatecentral2024monthly, author = {{Climate Central}}, title = {{Monthly Attribution Overview - September 2024}}, institution = {Climate Central}, year = {2024}, month = sep, url = {https://assets.ctfassets.net/cxgxgstp8r5d/61YskkL2WJimzoZ27rXdCT/ce65f863efe46046228f4d713da953e1/Climate_Central___September_2024_U.S._Attribution_Report.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }