Monthly Attribution Overview December 2024

In December 2024, 166 out of 191 analyzed U.S. cities were warmer than normal, with the most significant anomalies occurring in Montana. While long-term warming trends are evident—with 189 of 191 stations showing positive trends since 1970—daily climate attribution via the Climate Shift Index (CSI) remained generally low, though specific cities in Puerto Rico, Hawaii, and Alaska saw several days where temperatures were significantly more likely due to climate change.

• Temperature anomalies in December 2024 were elevated across much of the United States, with 166 of 191 analyzed cities recording temperatures warmer than normal. The most extreme anomalies were concentrated from Montana south to Texas, and cities in the Southwest, Northern Rockies, and Plains Region were on average more than 6°F warmer than average.
• Montana experienced the most anomalously warm cities in the country; the three hottest analyzed cities were Helena, Great Falls, and Billings, with Helena recording a temperature anomaly of 11.77°F.
• Long-term warming trends are prevalent in December, as 189 out of 191 analyzed ACIS stations have shown positive temperature trends since 1970. Presque Isle, Maine, is the fastest-warming station for December, increasing by an average of 9.2°F since 1970.
• Daily climate attribution using the Climate Shift Index (CSI) was generally low across most countries, as high CSI values are rare in December due to winter weather variability. However, San Juan, Puerto Rico, recorded 26 days at CSI 5, meaning temperatures were at least 5 times more likely to occur because of climate change.

APA

Climate Central (2025). Monthly Attribution Overview December 2024. https://www.climatecentral.org/report/monthly-attribution-overview-december-2024

Chicago

Climate Central. Monthly Attribution Overview December 2024. 2025. https://www.climatecentral.org/report/monthly-attribution-overview-december-2024.

Wikipedia

{{cite report |author=Climate Central |title=Monthly Attribution Overview December 2024 |date=2 January 2025 |url=https://www.climatecentral.org/report/monthly-attribution-overview-december-2024 |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{climatecentral2025monthly, author = {{Climate Central}}, title = {{Monthly Attribution Overview December 2024}}, institution = {Climate Central}, year = {2025}, month = jan, url = {https://www.climatecentral.org/report/monthly-attribution-overview-december-2024}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }