bluewave

It comes out before the NOAA maps but has been reasonably close based on recent experience to what the NOAA updates have been. The state of PA had their 3rd warmest June and July period on record at 71.8°. The summer ranking will be lower when NCEI updates in a few weeks since August was cooler.

It will probably come down to frontal timing. The GFS has 90° on Friday for the warm spots in NJ. The Euro has a slightly slower frontal passage so the 90° on Saturday. Won’t take much to beat guidance by a few degrees with how dry it has been.

The August maps won’t update for several more days on that site. But the summer maps on some other sites that have updated are the same pattern. Warm in the East and West with cooler in the middle. The prism maps already updated for JJA with numerous top 10 warmest summer rankings for the Northeast.

The main reason I use it is that my analysis and forecasts are based on the perspectives. So I need to compare it to what has happened in the period of record. But I understand that many seasonal forecasts are 1991-2020 departure based on where the areas of above and below temperatures are located. My guess from several years back that our next colder winter would only be colder relative to the much warmer 1991-2020 baseline worked out. As this past winter in the Northeast would have been slightly warmer based on earlier periods of record. DJF 2024-2025 Northeast 24.6° 1895-2000….+1.4° 1961-1990……+1.8° 1971-2000……+0.5° 1981-2010…….-0.3° 1991-2020……-1.2°

My area along the CT Shoreline finished with the 2nd highest number of 90° days at 15. The high of 98° in June set the new monthly all-time high by +2°. Overall the summer was the 4th warmest here with many top 10 warmest in recent years. So I was very grateful for the much cooler temperatures to end the summer. The low of 51° was the 7th coldest for the month of August. The drop from the record high dewpoints earlier in the summer really helped out. Time Series Summary for NEW HAVEN TWEED AP, CT - Jan through Dec Top 10 highest 90° days Click column heading to sort ascending, click again to sort descending. 1 2022 17 0 2 2025 15 121 3 2010 14 0 4 1977 13 100 5 2021 12 0 - 2020 12 2 - 2012 12 3 6 2013 11 0 7 2002 10 3 - 1952 10 0 8 2024 9 1 9 2023 8 1 - 2019 8 2 - 2018 8 3 - 2016 8 0 - 1955 8 0 10 2011 7 0 Time Series Summary for NEW HAVEN TWEED AP, CT - Month of Jun Highest monthly max temperature Click column heading to sort ascending, click again to sort descending. 1 2025 98 0 2 1957 96 0 3 2012 95 0 4 2021 94 0 5 2008 93 0 - 1974 93 0 - 1964 93 0 - 1953 93 0 - 1952 93 0 6 2024 92 0 - 1968 92 0 - 1966 92 0 - 1956 92 0 - 1949 92 0 7 1965 91 0 - 1963 91 0 8 2022 90 0 - 2020 90 0 - 2019 90 0 - 2013 90 0 - 2010 90 0 - 2003 90 0 Time Series Summary for NEW HAVEN TWEED AP, CT Top 10 Warmest Summer Click column heading to sort ascending, click again to sort descending. 1 2022 75.4 0 2 2024 75.2 0 3 2020 74.9 2 4 2025 74.5 0 5 2010 74.3 0 6 2021 74.2 0 7 2019 74.0 0 8 1977 73.8 31 9 2018 73.6 0 10 2012 73.5 0 Time Series Summary for NEW HAVEN TWEED AP, CT - Month of Jun Click column heading to sort ascending, click again to sort descending. 1 2024 72.9 0 2 2025 71.8 0 3 1976 71.4 0 4 2021 71.3 0 5 2010 71.0 0 6 1977 70.9 23 7 2008 70.8 0 8 2020 70.1 0 9 1957 69.9 0 10 2013 69.7 0 - 1949 69.7 0 Time Series Summary for NEW HAVEN TWEED AP, CT - Month of Aug Top 10 lowest monthly minimum temperature Click column heading to sort ascending, click again to sort descending. 1 1976 43 0 2 1965 45 0 3 1952 46 0 4 1964 48 0 - 1957 48 0 - 1956 48 0 - 1949 48 0 5 1971 49 0 - 1968 49 0 - 1948 49 0 6 1955 50 0 - 1953 50 0 7 2025 51 0 - 2006 51 0 - 2004 51 4

JJA 2023 was actually a little warmer against the long term averages. But since 2010-2025 has been so warm it felt cooler. You can see how this summer matched the 2010-2024 pattern with warmth in the East and West with cooler in the mid section of the nation. This is the same way that this winter felt colder by comparison to the much warmer winters since 15-16. But it was still warmer than the long term average in the Northeast.

Even with this cooler ending to August, it was still another top 10 warmest summer for many locations. This has been the case most summers since 2010. Plus the all-time June heat in the 100° to 105° range. So it was very nice to get a relaxation of this heat during August. The cooler conditions in May and August into the start of September prevented the warm spots from making a run on 50 days reaching 90° like 2022 and 2010. So we got lucky that the heat peaked early again in June and July. The Erin Cat 5 recurve and other wave breaks helped pull the trough into the East during recent weeks. My area actually ranked higher for 90° days this year than the warm spots like Newark. Time Series Summary for NEW HAVEN TWEED AP, CT - Jan through Dec Top 10 years 90° days Click column heading to sort ascending, click again to sort descending. 1 2022 17 0 2 2025 15 122 3 2010 14 0 4 1977 13 100 5 2021 12 0 - 2020 12 2 - 2012 12 3 6 2013 11 0 7 2002 10 3 - 1952 10 0 8 2024 9 1 9 2023 8 1 - 2019 8 2 - 2018 8 3 - 2016 8 0 - 1955 8 0 10 2011 7 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Top 10 years 90° days Click column heading to sort ascending, click again to sort descending. 1 2010 54 0 2 2022 49 0 - 1993 49 0 3 1988 43 0 4 2021 41 0 - 2002 41 0 - 1991 41 0 5 2016 40 0 - 1983 40 0 - 1959 40 0 6 1994 39 0 - 1944 39 0 7 2025 38 122 8 2005 37 0 - 1987 37 0 9 2018 36 0 - 1949 36 0 10 2015 35 0

We had a top 10 warmest summer here in the Northeast at many locations. Also top 10 for 90° days during the summer and 70° summer minimums along with record high dewpoints. Several spots also had a top 10 driest summer. All-time heat for June with several spots in the 102-105° range which was a first for the month of June. We have seen this theme frequently during the 2020s. Heat peaking earlier in the season and relaxing a bit relative to the early season during August some years like this one. Familiar new pattern this decade with summer heat in the West and East while cooler in the middle of the nation. For the period from 2010 to 2025 the Northeast has experienced 13 out of 16 warmer to record wam summers. Most summers have finished somewhere in the top 10 for warmth over this period. The last cooler summer relative to earlier periods was in 2014. But we haven’t had a significantly cooler summer relative to the past since 2009. That was our last top 10 coldest June into July period.

Started seeing some wave breaking activity right around the time we had the big cat 5 recurve with Erin a few weeks ago. So this helped to reinforce the cooler trough pattern in the East. It’s been nice having the trough in the Northeast from late August into early September following the record June and July heat. The record low pressure north of Alaska may have been a part of this pattern.

Yeah, numerous top 10 driest summer reports in the Northeast.

El Ninos don’t follow the pattern as closely. Some El Niños with weak snowfall starts like 23-24 follow up with below average snowfall. But some years like 15-16 with a T of snow in December did very well for the whole season.

My guess is that it’s related to La Niña winters typically being frontloaded by nature for cold and snow. A weak start to the snowfall continues for the whole season. With a snowy start continuing for the whole season. So if the stations near NYC stay under 4” in December, then it’s a below average snowfall signal for the whole season. Go above 4” in December and it has usually been a snowy season. This relationship has worked for 14 out of the last 15 La Ninas since 95-96 including the recent 24-25 La Niña winter season.

Something seems to have shifted with the drought pattern which emerged last fall. It used to be that rain events could be relied upon to beat model expectations. Now we seem to generally underperform longer range model expectations. When the wet patterns do materialize, then the heaviest is often localized with other areas not getting as much. So widespread soaking events have been more the outlier than the norm. Not sure yet if this is just a one year blip and we reverse again back to much wetter again down the road. But things have been getting very dry in Canada which we haven’t typically seen before. It’s probably too early to know if the wet pattern which began in 2003 is starting to get some pushback from recent drier tendencies. We also got some drier periods over this stretch but they didn’t last very long.

It used to work out that way more often before 2010-2011. But for some reason things have reversed since then. So the weaker RONI winters of the multiyear events turned out to be the warmer winters. https://www.cpc.ncep.noaa.gov/data/indices/RONI.ascii.txt DJF 2023 -0.83…warmest winter of the 3 year La Niña DJF 2022 -1.21 DJF 2021 -1.17 DJF 2018 -1.10 DJF 2017 -0.73…warmest winter of 2 year La Nina DJF 2012 -0.82…warmest winter of 2 year La Niña DJF 2011 -1.42

Flagstaff also had their 4th warmest summer following their warmest summer in 2024 with all 6 of the 2020s summers finishing in the top 10. Time Series Summary for Flagstaff Area, AZ (ThreadEx) Top 10 warmest summers dense rank sorting by temperature Click column heading to sort ascending, click again to sort descending. 1 2024 68.4 0 2 1981 66.6 0 3 2002 66.3 0 4 2025 66.1 1 - 2021 66.1 0 5 2020 65.8 0 - 2007 65.8 0 - 1974 65.8 0 - 1940 65.8 0 6 2018 65.6 0 7 2022 65.4 0 - 2008 65.4 0 - 1980 65.4 0 8 2012 65.3 0 - 1946 65.3 0 9 2023 65.2 0 - 2017 65.2 0 - 1996 65.2 0 - 1977 65.2 0 10 2013 65.1 0 - 1936 65.1 0

It wasn’t that much of a surprise. Just last year several spots were warmer in June than August. Most years when we have major heat in June and July August is cooler.

The minimum departure pattern over the last week looks similar to last January. Warmer to the north and cooler to the south. Matching the over the top warming pattern of recent years. The warming to the north was more pronounced back in January due the strong westerly flow off the warmer lakes. This event was primarily a radiational cooling one with strong surface high pressure and very low dewpoints.

The tree growth issue at Central Park over the ASOS has become even more pronounced during the 2020s. Notice how many rural sites like the Charlotteburg Reservior and Baiting Hollow now have more 90° days. I tried to find an approximate analog from the past for 90 days when there wasn’t a tree growth issue in NYC. Notice how the other sites closer to NYC in more urban settings had a similar number of 90° days this year so far and in 1949. So based on the relationship of 90° days between 1949 and 2025 using LGA and EWR, NYC probably had 27-29 days reaching 90° instead of the reported 14 days value in 2025. Data for January 1, 2025 through August 31, 2025 Click column heading to sort ascending, click again to sort descending. NJ NEWARK LIBERTY INTL AP WBAN 38 NJ HARRISON COOP 36 NJ TETERBORO AIRPORT WBAN 36 NJ TETERBORO AIRPORT COOP 35 NJ CALDWELL ESSEX COUNTY AP WBAN 32 NY LAGUARDIA AIRPORT WBAN 26 CT MERIDEN MARKHAM MUNICIPAL AP WBAN 24 NY PORT JERVIS COOP 22 CT DANBURY MUNICIPAL AP WBAN 21 CT DANBURY COOP 21 NJ CHARLOTTEBURG RESERVOIR COOP 20 NY BAITING HOLLOW COOP 19 CT NORWICH PUBLIC UTILITY PLANT COOP 18 NY ST. JAMES COOP 17 NY WESTCHESTER CO AP WBAN 16 NY JFK INTERNATIONAL AIRPORT WBAN 15 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 15 CT NEW HAVEN TWEED AP WBAN 15 NY NY CITY CENTRAL PARK WBAN 14 Data for January 1, 1949 through August 31, 1949 Click column heading to sort ascending, click again to sort descending. NJ PATERSON COOP 39 NJ PLAINFIELD COOP 38 NJ LITTLE FALLS COOP 37 CT WATERBURY ANACONDA COOP 36 NY PORT JERVIS COOP 36 NJ RUTHERFORD COOP 36 NY WEST POINT COOP 35 NY BEDFORD HILLS COOP 35 NJ NEWARK LIBERTY INTL AP WBAN 35 NJ CANOE BROOK COOP 35 NJ ELIZABETH COOP 33 NJ WANAQUE RAYMOND DAM COOP 32 NY OSSINING SING SING COOP 32 NY CARMEL COOP 32 CT WATERBURY CITY HALL COOP 32 NJ RIDGEFIELD COOP 32 NY SCARSDALE COOP 29 NY NY CITY CENTRAL PARK WBAN 29 NY LAGUARDIA AIRPORT WBAN 28 CT NORWALK COOP 27 NY DOBBS FERRY-ARDSLEY COOP 26 NY STEWART FIELD WBAN 26 NY WALDEN 2 NE COOP 25 CT BRIDGEPORT COOP 25 CT MOUNT CARMEL COOP 22 CT MIDDLETOWN 4 W COOP 22 NJ CHARLOTTEBURG RESERVOIR COOP 21 NY RIVERHEAD RESEARCH FARM COOP 21 CT GREENWICH COOP 20 NY HEMPSTEAD MALVERNE COOP 19 NY MINEOLA COOP 19 NY WESTCHESTER CO AP WBAN 19 NY SETAUKET STRONG COOP 19 NY FARMINGDALE 2 NE COOP 18 NY JFK INTERNATIONAL AIRPORT WBAN 18

Several spots had another top 5 and top 10 warmest summer which has become the norm since 2010. Time Series Summary for SUSSEX AIRPORT, NJ Click column heading to sort ascending, click again to sort descending. 1 2024 72.8 0 - 2020 72.8 2 2 2025 72.5 1 3 2021 72.3 0 - 2005 72.3 0 4 2022 72.0 5 5 2018 71.9 0 6 2016 71.6 1 7 2010 71.5 2 8 2011 71.4 4 9 2019 71.2 0 10 2014 71.0 0 Time Series Summary for SOMERSET AIRPORT, NJ Click column heading to sort ascending, click again to sort descending. 1 2005 75.1 3 2 2024 74.9 0 3 2022 74.6 0 4 2020 74.5 0 5 2021 74.3 0 - 2016 74.3 0 6 2010 74.0 0 7 1999 73.8 8 8 2011 73.6 1 9 2025 73.4 1 - 2019 73.4 0 10 2018 73.3 0 - 2002 73.3 2 Time Series Summary for WESTCHESTER CO AP, NY Click column heading to sort ascending, click again to sort descending. 1 1995 75.1 43 2 1999 74.3 7 3 2022 74.0 0 - 1983 74.0 1 4 2024 73.8 0 - 2010 73.8 2 5 2016 73.7 0 6 2020 73.4 0 7 2025 73.3 1 8 2005 73.2 2 - 1966 73.2 0 9 1952 73.1 0 10 2018 73.0 0 Time Series Summary for CHARLOTTEBURG RESERVOIR, NJ Click column heading to sort ascending, click again to sort descending. 1 2024 72.8 0 2 2020 72.5 0 3 2025 72.3 1 4 2010 72.2 2 5 2022 72.0 0 6 2005 71.8 0 7 2021 71.6 0 - 2018 71.6 1 8 1949 71.5 0 - 1934 71.5 6 9 2019 71.4 0 - 2016 71.4 0 - 1894 71.4 12 10 1991 71.3 0 Time Series Summary for IGOR I SIKORSKY MEMORIAL AIRPORT, CT Click column heading to sort ascending, click again to sort descending. 1 2016 75.4 0 2 2020 75.3 0 3 2010 75.0 0 4 2024 74.5 0 5 2022 74.4 0 6 2018 74.3 0 7 2021 74.2 0 - 2012 74.2 0 8 2025 74.0 1 - 2019 74.0 0 - 2011 74.0 0 - 1994 74.0 0 - 1993 74.0 0 9 2005 73.9 0 10 2013 73.8 0 - 1973 73.8 0 Time Series Summary for NEW HAVEN TWEED AP, CT Click column heading to sort ascending, click again to sort descending. 1 2022 75.4 0 2 2024 75.2 0 3 2020 74.9 2 4 2025 74.5 1 5 2010 74.3 0 6 2021 74.2 0 7 2019 74.0 0 8 1977 73.8 31 9 2018 73.6 0 10 2012 73.5 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY Click column heading to sort ascending, click again to sort descending. 1 2010 74.7 0 2 2022 74.6 0 - 2020 74.6 0 3 2025 74.5 1 - 1999 74.5 0 4 2016 74.4 0 5 2024 74.2 0 6 2011 73.9 0 7 2019 73.8 0 8 2021 73.7 0 9 2018 73.5 0 - 2005 73.5 0 10 2013 73.4 0 Time Series Summary for MONTAUK AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 2024 74.4 3 2 2025 73.9 5 3 2020 73.0 0 4 2022 72.7 0 5 2010 72.6 1 6 2011 72.5 1 7 2015 72.3 8 8 2021 72.0 1 9 2012 71.9 0 - 2005 71.9 0 10 2018 71.7 0

Much lower summer pressures over the Arctic since 2012 halted the rate of historic sea ice decline from 2007-2012 with the record Arctic dipole pattern those years. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2012GL053268 Thus we can say that a six year run of near one standard deviation negative excursions (2007–2012) is unique in the 63 year record. To further test the significance of the 2007–2012 AD patterns we randomly generated 10,000 time series, each with 63 points to match the observed time series and with a normal distribution without autocorrelation. For this simple calculation, the chance for having five consecutive values with a negative AD of magnitude greater than 1.0 standard deviation units in a sample size of 63 is rare, less than 1 in a 1000.

Yeah, reduction of smoke with this Canadian airmass and dewpoints in the 40s are doing the trick.

The main detriment to snowfall in general for the I-95 corridor since 18-19 has been the warm storm tracks. So while this winter averaged 34.8° in NYC, the 11 days on which .25+ of precipitation fell averaged 41.0°. For 50”+ snowfall seasons and La Niña background NYC needs to average closer to 32.0° and have cold storm tracks and storm days when the bulk of the precipitation falls. Even during the warmer winters of 15-16, 16-17, 17-18, and 20-21,the colder storm tracks and storm days allowed NYC to finish in the respectable 30-40” range for snowfall. But the lack of cold for a DJF average near 32.0° was too warm to go 50”+. Since 18-19 we have had both a warm background pattern and warm storm tracks. So this is why the 7 year snowfall totals have been at record low levels. I am hoping for the remainder of the 2020s we can see some bounce off these extreme low values. But expecting a repeat of 2010-2018 is probably a very low probability outcome absent some major volcanic event.

Another cool crisp late August morning just east of HVN at 58°. I really enjoy how well this area near the LI Sound cools off at night compared to the LI South Shore. The low of 51° a few days ago was the lowest August minimum since 2006. These much lower dewpoints allowing for the cooler mornings have been a nice treat following the record June into July heat and humidity. My maxes this month have been +1.8° and my mins have been -1.5°. So the month has been +0.2° so far.

The other important thing to mention is that there have only been 2 La Nina winters for NYC in the last 50 years with 50”+ in NYC. These were 1995-1996 and 2010-2011. The NYC winter average temperature in 1995-1996 was 32.2° and in 2010-2011 was 32.8°. Both those winters occurred before the warming jump over the last 10 years. The current 10 winter average temperature in NYC since 2015-2016 is the highest on record at 38.2° and +1.8° over the previous warmest 10 winter run. So the past winter which was the coldest of the last decade was only 34.8°. This was 2.0°+ warmer than the 1995-1996 and 2010-2011 winters. I bring up the La Niña factor since we have been in a persistent La Niña background state through the record warming of the WPAC. So this has been interfering with allowing a true El Niño modoki state like we had in 2009-2010 which was a little an over freezing at 33.8°. So the modoki allowed for the heavier snows during a warmer winter than the 2 La Ninas in 1995-1996. The record warming WPAC prevented the El Niño modoki from forming in 2018-2019 and 2019-2020. Even the snowy La Niña winters of 17-18 and 20-21 were too warm for NYC to make it to 50”. But outlying areas which have different requirements to reach 50” did. So my guess is that this current much warmer regime will make it challenging for NYC Central Park station to reach 50” again. But outlying stations which get colder could possibly do it.