December 2025 OBS and Discussion

[donsutherland1]

New York City finished December 1-10 with a mean temperature of 34.1F (1.2C). That was the coldest first 10 days of December since 2007 and sixth coldest since 2000.

A quick look at the guidance shows that a light snow event (probably 1"-3") across the New York City area is likely on Sunday. Given how snow events have been challenging to come by in recent years, to some it might seem like a big event. Even the previously bone-dry NBM shows 0.12" QPF. 

[bluewave]

7 hours ago, JerseyWx said:

People will say it's my "heat tolerance," but out my way I seldom use the AC in May and September, outside of short stretches.  In recent years we've even gone well into June without it.  Before we got that heatwave this past June in fact it was quite cool.  The city is outrageous with how it retains heat.  Sometimes I see they are close to 90 at midnight whereas I'll be in the mid 70's.

I grew up in Long Beach on the South Shore and we only needed the AC a handful of times back in the 1970s. First for the August 1973 heatwave and then the July 1977 heatwave. We gradually increased the AC usage during the 1980s and especially the early 1990s.

By the time we reached 2010, we had three ACs running much of the time compared to only one in the 1970s. Plus there was a rapid expansion of central AC even in Long Beach when it was a rarity near the shore in the 1970s. This is one of the reasons that HVAC is such a good career opportunity for people due to the increased demand in a warming world.

As for the UHI issue, there was a 10°+ difference between NYC during 1896 heatwave and the surrounding countryside. This mostly occurs with summer heatwaves where the city absorbs more heat during the day. It also occurs during calm and clear nights with radiational cooling.

The growth of skyscrapers in Western Brooklyn and Queens certainly changes the character of the neighborhood and of course you can see the change in the skyline since around 2004.

But prior to that that area had densely packed lower rise buildings built of bricks. These new high rises are mainly glass and steel which absorb significantly less solar energy than bricks do.

Plus a cluster of tall buildings will create a big area of shade which prevents the streets and sidewalks from absorbing as much heat as they did with smaller buildings with less shadows.

The warmest parts of NYC are in Queens near spots like Corona were small to medium size brick structures dominate. So changing from lower rise brick and concrete structures to skyscrapers may not change the UHI much in Western Brooklyn and Queens to really be noticeable to residents there. That’s why I said a drop in the bucket to what was already one of the largest UHI zones in North America.

The rural and suburban areas have warmed at a similar rate to places like Corona Queens over the years. So this is why both areas require more summer AC usage than they did during the 1970s.

My guess is that the higher dewpoints and maybe stronger winds are probably why a rural spot like the Charlotteburg Reservoir has seen a steeper increase in low temperatures than LGA since 1981.

[North and West]

I grew up in Long Beach on the South Shore and we only needed the AC a handful of times back in the 1970s. First for the August 1973 heatwave and then the July 1977 heatwave. We gradually increased the AC usage during the 1980s and especially the early 1990s.
By the time we reached 2010, we had three ACs running much of the time compared to only one in the 1970s. Plus there was a rapid expansion of central AC even in Long Beach when it was a rarity near the shore in the 1970s. This is one of the reasons that HVAC is such a good career opportunity for people due to the increased demand in a warming world.
As for the UHI issue, there was a 10°+ difference between NYC during 1896 heatwave and the surrounding countryside. This mostly occurs with summer heatwaves where the city absorbs more heat during the day. It also occurs during calm and clear nights with radiational cooling.
The growth of skyscrapers in Western Brooklyn and Queens certainly changes the character of the neighborhood and of course you can see the change in the skyline since around 2004.
But prior to that that area had densely packed lower rise buildings built of bricks. These new high rises are mainly glass and steel which absorb significantly less solar energy than bricks do.
Plus a cluster of tall buildings will create a big area of shade which prevents the streets and sidewalks from absorbing as much heat as they did with smaller buildings with less shadows.
The warmest parts of NYC are in Queens near spots like Corona were small to medium size brick structures dominate. So changing from lower rise brick and concrete structures to skyscrapers may not change the UHI much in Western Brooklyn and Queens to really be noticeable to residents there. That’s why I said a drop in the bucket to what was already one of the largest UHI zones in North America.
The rural and suburban areas have warmed at a similar rate to places like Corona Queens over the years. So this is why both areas require more summer AC usage than they did during the 1970s.
My guess is that the higher dewpoints and maybe stronger winds are probably why a rural spot like the Charlotteburg Reservoir has seen a steeper increase in low temperatures than LGA since 1981.

tl;dr it’s warmer now?


.

[WeatherGeek2025]

partly cloudy and cold here in White Plains. 29 degrees

[bluewave]

5 hours ago, donsutherland1 said:

New York City finished December 1-10 with a mean temperature of 34.1F (1.2C). That was the coldest first 10 days of December since 2007 and sixth coldest since 2000.

A quick look at the guidance shows that a light snow event (probably 1"-3") across the New York City area is likely on Sunday. Given how snow events have been challenging to come by in recent years, to some it might seem like a big event. Even the previously bone-dry NBM shows 0.12" QPF. 

It’s possible that some areas to our south with the strong cold departures through the 10th could finish December close to average with the coming warm up.

This also fits the pattern since at least the 1990s of the 2nd half of December warming at a faster rate than the 1st half in our area.

 

[SACRUS]

33 / 13  with 0.12 in the bucket yesterday.  Cold overall the next 6 days, peaking Mon/Tue.  Snow squall / shower/light snow overnight Sat into Sun likely a coating to 2/3 inches with some areas a bit more.  Moderation by the 18th and into Christmas week to and above normal.  Beyond the 25th forecasts maintain very cold just to the north so looking to finish the the last week leading to new years at or below normal after the 18-25 warmup.

 

[Krs4Lfe]

17 minutes ago, bluewave said:

It’s possible that some areas to our south with the strong cold departures through the 10th could finish December close to average with the coming warm up.

This also fits the pattern since at least the 1990s of the 2nd half of December warming at a faster rate than the 1st half in our area.

 

Verbatim based on those temperature anomaly maps New York City is pretty much right around average on December 26, while the rest of the country is torching. The craziest statistic is what you just mentioned above is where places down south that are running up to 8° below normal this month could finish close to average because much of the country will be in spring like warmth during Christmas week. Reminds me a lot of December 2022 colder than normal month overall a big-time arctic freeze a few big storms across the north US and then after Christmas, we torched right through right through New Year’s and through the rest of January.

[SACRUS]

Records:

Highs:

EWR: 69 (2021)
NYC: 66 (2021)
LGA: 67 (2021)
JFK: 67 (1971)


Lows:

EWR: 11 (1977)
NYC: 6 (1880)
LGA: 14 (1988)
JFK: 13 (1988)

 

Historical:

1862: As the Battle of Fredericksburg commenced, the Union troops were aided by fog in building of pontoon bridges and moving troops into position. (Ref. Wilson Wx. History)

1864: High winds move the newly erected Capitol Dome.

1905: The highest temperature ever recorded in South America was recorded at Rivadavia, Argentina hit 120 °F. (Ref. Wilson Wx. History)

1932 - Very cold weather prevailed along the West Coast. San Francisco received 0.8 inch of snow, and at the airport the temperature dipped to 20 degrees. At Sacramento CA, the mercury dipped to 17 degrees to establish an all-time record low for that location. Morning lows were below freezing from the 9th to the 15th at Sacramento, and the high on the 11th was just 34 degrees. The cold wave dealt severe damage to truck crops and orange groves in the Sacramento Valley. (David Ludlum) (The Weather Channel)

1949: A tornado causing F2 damage moved through Marion County, Missouri. Damage totaled $200,000 in a 20-block area of Hannibal with a few homes completely unroofed. 12 people were injured along the tornado's path. In central Missouri, one of the worst ice storms of the century struck leaving over 2 inches of ice in some locations. (Ref. Wilson Wx. History)

1949: A tornado causing F2 damage moved through Marion County, Missouri. Damage totaled $200,000 in a 20-block area of Hannibal with a few homes completely unroofed. 12 people were injured along the tornado's path. In central Missouri, one of the worst ice storms of the century struck leaving over 2 inches of ice in some locations. (Ref. Wilson Wx. History)

1972: A strong upper level trough remained in pace from the Rockies to the West Coast that brought extreme record low temperatures for the date including: Winnemucca, NV: -33 °F, Elko, NV: -28 °F, Pocatello, ID: -26 °F (broke previous record by 16 degrees), Lander, WY: -26 °F, Ely, NV: -24 °F, Boise, ID: -22 °F (broke previous record by 18 degrees), Sheridan, WY: -20 °F, Burns, OR: -19 °F, Moline, IL: -18 °F, Rockford, IL: -18 °F, Green Bay, WI: -17 °F, Madison, WI: -17 °F, Reno, NV: -15 °F, Minneapolis, MN: -14 °F, Dubuque, IA: -13 °F, Rapid City, SD: -13 °F, Salt Lake City, UT: -11 °F, Milwaukee, WI: -10 °F, Alpena, MI: -8 °F, Chicago, IL: -5 °F, Fresno, CA: 25 °F-Tied, San Francisco Airport, CA: 26 °F, Santa Maria, CA: 26 °F-Tied, Long Beach, CA: 34 °F-Tied and Downtown Los Angeles, CA: 35 °F. The high temperature at Victorville, CA was 32 °F, tying their lowest high temperature on record with 1/30/1957 and 12/15/1957.
Upper level high pressure off the southeast coast brought record highs to a few locations including: Charleston, SC: 83 °F, Macon, GA: 82 °F and Columbus, GA: 78 °F. (Ref. Wilson - Additional Temperatures Listed On This Link)

1979: Temperature dropped in Roseville, MN from 48 degrees at 2 pm to zero by dawn. (Ref. AccWeather Weather History)

1983: Nine cars fell through the ice at the same time on Buffalo Lake, MN in central Minnesota. There was only 5 to 6 inches of ice on the lake. (Ref. Wilson Wx. History)

1985: Phoenix, AZ recorded their first measurable snow since 1939. (Ref. AccWeather Weather History)

1987 - Low pressure over southwestern Ontario, Canada, brought snow and gusty winds to the North Central U.S. Winds gusted to 62 mph at Riverton WY. Snow and high winds in eastern North Dakota reduced visibilities to less than one hundred feet at times. Warm weather prevailed across the Southern Plains Region. Half a dozen cities reported record high temperatures for the date, including Del Rio TX with a reading of 89 degrees. Laredo TX and Kingsville TX tied for honors as hot spot in the nation with afternoon highs of 92 degrees. (The National Weather Summary)

1988 - Arctic cold invaded the central and eastern U.S. Sault Ste Marie MI reported a record low of 14 degrees below zero, and International Falls MN was the cold spot in the nation with a low of 25 degrees below zero. Temperatures remained below zero all day over parts of eastern Upper Michigan and northern New England. (The National Weather Summary)

1989 - Strong Santa Ana winds developed across southern California and parts of central California. Winds in Kern County of central California gusted to 100 mph near Grapevine. The high winds reduced visibilities to near zero in the desert areas, closing major interstate highways east of Ontario CA. (Storm Data) (The National Weather Summary)

1990: Dense fog formed along the Hiwassee River near Calhoun, TN, dropping the visibility along a 3-mile stretch of I-75 to zero at times. 12 people were killed in a massive 83 vehicle pile-up. (Ref. AccWeather Weather History)

 

1992:A complex storm system moved eastward from the Gulf Coast of Texas to eastern Georgia on December 9 and 10th. In the next 24 hours, the low-pressure system moved to the Chesapeake Bay and rapidly intensified. This system produced gale force winds with gusts exceeding hurricane force affected not only the Mid-Atlantic coastline but also as far southwest as the southern Appalachians where trees were downed and roofs damaged. This storm also produced 20 to 30-foot waves in Massachusetts on December 12 and 13th. Precipitation amounts varied considerably. Rainfall amounts of 8 inches occurred in southeastern Massachusetts, while several areas in New York, Massachusetts, Pennsylvania, and Maryland recorded more than 30 inches of snow. Precipitation ended during the evening hours on the 12th. Ten deaths resulted from the storm with insured losses totaling near $850 million and non-insured losses near $2 billion.


1995: Monster storm hits the Pacific Coast. 1 1/2 million without power from California to Washington and 6 people killed. (Ref. AccWeather Weather History)


2000: A blizzard struck areas of the Midwest, Missouri Valley into Michigan. Strong winds sustained at 20 to 40 mph with gusts up to 50 mph created blizzard and near whiteout conditions, thunder and lightning and dangerous wind chills as low as -40 °F. Snowfall totals generally ranged from 6 to 16 inches with drifts several feet high in some areas. 10 to 15 inches occurred in Cook and DuPage Counties of the Chicago area, with 6 to 10 inches as far south as central Illinois. Freezing rain and sleet mixed in further south keeping accumulations down. 8 to 11 inches of snow fell across southwestern Missouri with amounts 12 to 14 inches reported from Joplin through Springfield to Joplin, MO. Areas near West Plains, MO received a mixture of snow and sleet keeping accumulations down to 4 to 8 inches. Some snowfall totals included: Cassopolis, IN: 16 inches, Elkhart, Goshen, IN: 14 inches, Niles, St. Joseph & South Bend, IN: 12 inches, O’Hare Airport in Chicago, IL: 9.5 inches, Rockford, IL: 8.3 inches, Oelwein, IA: 8 inches, Muscoda, WI: 7.5 inches, Cuba City, WI: 7 inches and Mt. Sterling, WI: 7 inches The 14.5 inches of snow that fell at Lansing, MI is the heaviest on record for any December day. The 14.2 at Grand Rapids, MI is also a record for any day in December and contributed to December 2000 being the snowiest month ever recorded at those locations. 19 people in the Chicago area died while shoveling snow, from heart failure or hypothermia. (Ref. Wilson Wx. - Additional Information)
 

2008 - A rare snowstorm swept across parts of south Louisiana and Mississippi, blanketing the area with snow. Nearly 8 inches of snow fell over parts of Louisiana. These conditions caused schools and bridges to close and left thousands of residents without power (Associated Press). (NCDC)

2010 - The "Pineapple Express" - a meteorological event where southwest winds bring warm, moist air to the U.S. West Coast - produced record rainfall to the Pacific Northwest during December 11th-12th. Seattle experienced record daily rainfall two days in a row. The Seattle-Tacoma International Airport recorded 1.42 inches of rain on the 11th, breaking the old daily record of 1.32 inches set in 1955. The next day, 2.19 inches fell, breaking the daily record of 1.70 inches set in 1966. The Stillaguamish River in western Washington state reached 21.06 feet at Arlington, tying the record set in November 2006. Flood stage for the river is 14 feet. The storm system also brought record warmth to the area. On December 14th, the temperature at Seattle-Tacoma International Airport reached 57, breaking the old daily record of 55 set in 2004. (NCDC)

[donsutherland1]

31 minutes ago, bluewave said:

It’s possible that some areas to our south with the strong cold departures through the 10th could finish December close to average with the coming warm up.

This also fits the pattern since at least the 1990s of the 2nd half of December warming at a faster rate than the 1st half in our area.

 

Yes, that's true. Parts of the FL might wind up having a top 10 warmest December. And many records are being set out West.