November 2025 OBS Discussion

[donsutherland1]

A generally milder than normal pattern will likely continue through next Wednesday when a system could bring a period of rain. However, exceptional warmth appears unlikely. 

The closing days of November will likely turn colder. There is potential for New York City's Central Park to experience its first freeze of 2025. The 1991-2020 normal first data is November 21. The 1961-1990 baseline was November 11. Last winter's first freeze occurred on November 30.

The opening days of December will turn milder. However, colder conditions could begin to develop during the second half of that week and continue through the second week of December. Severe cold appears unlikely through at least the first 10 days of December. Afterward, the pattern evolution will depend, in part, on how the imminent stratospheric warming event propagates. 

Meanwhile, today will be Central Park's 1,395th consecutive day without daily snowfall of 4" or more. That breaks the record of 1,394 days was set during February 22, 1929 through December 16, 1932. That stretch ended with 6.7" daily snowfall on December 17, 1932.

The ENSO Region 1+2 anomaly was -0.7°C and the Region 3.4 anomaly was -0.7°C for the week centered around November 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.16°C and the ENSO Region 3.4 anomaly has averaged -0.65°C. La Niña conditions will likely continue through at least mid-winter.

The SOI was -1.40 today. The fall of 39.57 points was the largest such fall since April 27, 2006 when the SOI fell 42.35 points. It was also the fourth largest decline on record. 

The preliminary Arctic Oscillation (AO) was -0.384 today. 

Based on sensitivity analysis applied to the latest guidance, there is an implied 90% probability that New York City will have a cooler than normal November (1991-2020 normal). November will likely finish with a mean temperature near 46.7° (1.3° below normal). 

Supplemental Information: The projected mean would be 1.0° below the 1981-2010 normal monthly value.