December 2025 OBS and Discussion

[cleetussnow]

1 hour ago, brooklynwx99 said:

yeah, legitimately exciting... that -NAO is uptrending, too. the 5-7th is our first legit shot at a larger region-wide storm. pattern becomes even more favorable after that, too

I’m more bullish this winter, but the 10-15 day patterns have been a let down in recent years.  The block has got my attention so let’s see if a KU emerges.  The pattern for January is at least for our region is vastly differently than the weeklies a couple weeks back.  What a flip flop.  

[IrishRob17]

1 hour ago, MANDA said:

Can you imagine what a heating bill would look like these days with a mean monthly temp of 25?   Have to believe it would cause hardship for many.

They were tougher back then IMO. I’d bet people just put more layers on and kept the heat lower in general. I work with people that remote start their car from their work desk at the end of the day so the car is the perfect temp for them before they even open the car door to drive home. 25 degrees now after a high of 26 under gray skies and a decent snowpack, what a winter day. 

[Nibor]

Man some good looking stuff on the long range euro. Hopefully this is the winter we end the “good pattern bad results” regime we’ve been in. 

[coastalplainsnowman]

5 hours ago, bluewave said:

50°+ warm ups with or without rain have become much more common prior to and following snow events here than they used to be. 

Granted I'm on Long Island, but I can probably count on one hand the number of years in the last 45 that we had significant snowcover last until the next big storm. New snow on top of old snow has always been quite rare.  93/94 of course is one such year, but even 95/96 notably was not.  In the 80s we had a few years where the snow from a moderate clipper lasted a few weeks in a very cold month, but again the Blizzard of '83 year was practically snowless right up to that storm, and was mild almost immediately after it.  Not saying the trend hasn't been toward more frequent mild spells, but it was almost never anything close to wall-to-wall winter around here.

[bluewave]

6 hours ago, psv88 said:

It’s December. The last event was mid December. There’s never a long lasting snowpack for all of december  

We have had longer lasting December snowpack in the past with other 10”+ snowfall Decembers on Long Island without a big warm up and rain following the heavier snows.

But these warm ups and rain following the heavier snows have become more common in December and the other winter months that we have had heavier snows. 

Unfortunately, Long Island weather records don’t go back as far as other spots across the region. But the snowfall this December isn’t that far from what used to be normal at spots with longer periods of record in the past colder climate era. Those colder era Decembers didn’t have the magnitudes of the warm ups with rain. So they had better snowfall retention for what fell relative to today.

 

[SnowGoose69]

4 minutes ago, coastalplainsnowman said:

Granted I'm on Long Island, but I can probably count on one hand the number of years in the last 45 that we had significant snowcover last until the next big storm. New snow on top of old snow has always been quite rare.  93/94 of course is one such year, but even 95/96 notably was not.  In the 80s we had a few years where the snow from a moderate clipper lasted a few weeks in a very cold month, but again the Blizzard of '83 year was practically snowless right up to that storm, and was mild almost immediately after it.  Not saying the trend hasn't been toward more frequent mild spells, but it was almost never anything close to wall-to-wall winter around here.

Does not happen often.  93/94 obviously 2/8 and 2/11 is the most memorable case.  95-96 I do not recall any really, seemed like the close together events were small and melted and the big ones had separation and we had a massive thaw too.  09-10 I think had a couple of instances.

[psv88]

14 minutes ago, SnowGoose69 said:

Does not happen often.  93/94 obviously 2/8 and 2/11 is the most memorable case.  95-96 I do not recall any really, seemed like the close together events were small and melted and the big ones had separation and we had a massive thaw too.  09-10 I think had a couple of instances.

It happened a lot from 2010-2015.

those 5 years had many storms of snow on snow. I want to say 2014-2015? Insane snow cover and repeated snow in snow. I think at one point we had snow from like 5 different snows down at once. 

[bluewave]

24 minutes ago, coastalplainsnowman said:

Granted I'm on Long Island, but I can probably count on one hand the number of years in the last 45 that we had significant snowcover last until the next big storm. New snow on top of old snow has always been quite rare.  93/94 of course is one such year, but even 95/96 notably was not.  In the 80s we had a few years where the snow from a moderate clipper lasted a few weeks in a very cold month, but again the Blizzard of '83 year was practically snowless right up to that storm, and was mild almost immediately after it.  Not saying the trend hasn't been toward more frequent mild spells, but it was almost never anything close to wall-to-wall winter around here.

That’s due to the weather records not going back far enough in time on Long Island.

Other spots like Newark with records back as far as the 1840s showed that something much closer to wall to wall cold and snow was the norm.

The 30 year average seasonal snowfall at Newark was 43.7” with an average winter temperature of 30.4”.

[GaWx]

2 hours ago, donsutherland1 said:

1917 also had a mean temperature of 25.0° for December 

 

Corrected Table:

Note: The initial table was constructed from summing daily snowfall amounts. Not all daily amounts are in the NYC climate record. Thus, doing so understates the monthly figures. Here's the correct table using the monthly figures.

 For -ENSO (17 seasons):

1872 10.6

1874 14.5

1886 6.6

1893 9.4

1903 15.6

1909 11.1

1915 0.7

1916 5.8

1917 13.2

1922 24.5

1926 5.7

1933 0.1

1942 9.5

1944 12.3

1995 26.1

2000 8.3

2010 36.0

 

Mean/median: 12.4/10.6

 Interestingly, the lowest 2 Jans and highest 3 Jans were -ENSO.

[psv88]

Overall this December gets an A-

14” of snow, cold but a few warmer days mixed in to allow for outdoor activities. Lots of snow on the ground when holiday lights up. Really a very good month

[donsutherland1]

New York City's largest snowstorm since January 28-29, 2022 has now departed. Even as precipitation dried up for several hours last evening, Central Park still wound up with 4.3" of snow while JFK Airport, LaGuardia Airport, and Newark all saw 4" or more of snow. Many parts of southwestern Connecticut and Long Island saw 6" or more.

Tomorrow will turn somewhat milder as a storm heads for the Great Lakes. Showers and possibly periods of rain will develop late tomorrow and continue into early Monday. The temperature will likely reach the upper 40s to perhaps lower 50s on Monday before colder air moves in behind the departing system.

The remainder of December will see cooler than normal days. Below normal temperatures will continue into at least the middle of the first week of January. Some flurries or snow showers are possible late on January 1 into January 2.

December 2025 will very likely finish with a maximum monthly temperature below 60° in New York City. The last time that happened was in 2019 when the monthly high was 58°. If 2025 has a monthly high below 60°, that would be only the fifth such occurrence since 2000 (2003, 2004, 2005, and 2019 are the cases since 2000).

The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.8°C for the week centered around December 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.40°C and the ENSO Region 3.4 anomaly has averaged -0.68°C. La Niña conditions will likely continue through at least mid-winter.

The SOI was +14.69 today. 

The preliminary Arctic Oscillation (AO) was -1.006 today. 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 100% probability that New York City will have a cooler than normal December (1991-2020 normal). December will likely finish with a mean temperature near 33.9° (5.2° below normal). That will make December 2025 the coldest December since 2010 when the monthly mean temperature was 32.8°. It would also make 2025 the third coldest December since 2000.

Supplemental Information: The projected mean would be 3.5° below the 1981-2010 normal monthly value.