donsutherland1

Around September 18th.

Islip reached 82° today. That was its fifth 80° or above high during the second half of September. The last time there were at least as many such days during the second half of September was in 2017 when there were eight such days. The five days is also tied with 1998 and 2016 for the fifth highest number on record for the second half of September.

As of 4:30 pm, some showers were working their way into southern New Jersey. Cape May was receiving light rain. Some of these showers could each the New York City area tonight. Showers and light rain are possible tonight into tomorrow. Rainfall amounts should be light. Above normal temperatures will continue through the remainder of September. The start of October could see the arrival of the coolest air mass so far this season, but temperatures will likely quickly moderate. The guidance and historical experience following a second half September mean temperature of 70° or above suggest that October will be warmer than normal in the New York City area. The two most recent Octobers with a cooler than normal first half like 2025 and a second half with a mean temperature of 70° or above were: 2017 (October mean temperature: 64.1° and October 2019: October mean temperature 59.9°). The probability that TD9 will approach the South Carolina coast but then turn out to sea from there is increasing on account of the expected Fujiwhara interaction with the stronger Humberto. That is now the most likely outcome, even as there remains a possibility of landfall. Even without landfall, the storm would bring periods of heavy rain, gusty winds, and pounding surf to coastal areas. The ENSO Region 1+2 anomaly was 0.0°C and the Region 3.4 anomaly was -0.4°C for the week centered around September 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.03°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. La Niña conditions will likely develop during mid- or late-autumn. The SOI was +2.85 today. The preliminary Arctic Oscillation (AO) was +0.807 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 99% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.3° (1.1° above normal). Supplemental Information: The projected mean would be 2.3° above the 1981-2010 normal monthly value.

Missing dates. I have redone the file. I had forgotten to exclude months with missing days.

Sorry, I pasted from the table early in this thread and accidentally overlooked my note. There were missing days. Note: The highest average maximum temperature at Newark for a September that is missing no daily records is 83.3°, which was set in 2005.

1983 actually does not hold the record for mean high during September, but does hold the record for most 90° or above days at a number of local sites.

The New York City area can still see both big snowstorms and snowy winters and that will be the case for decades to come even if/as seasonal snowfall declines.

It has a very weak correlation. I don't think it's of much predictive value. It should also be noted that some more recent research suggests that it is lower September-October Siberian snow cover that translates into a weaker polar vortex during late winter and early spring while increased Siberian snow cover (September–October) leads to a stronger polar vortex in late winter and early spring. For example: The reduced snow cover benefits a deceleration of the circumpolar westerlies, the sea ice loss in the Barents-Kara Seas, the positive Pacific-North American pattern, and the negative Aleutian-Icelandic Low Seesaw pattern, which amplify the intensity of planetary waves propagating upward into the stratosphere. The enhanced planetary waves are characterized by the stratospheric dipole-like pattern during the preceding October and December and contribute to the continuous weakening of the polar vortex from January to March. https://www.sciencedirect.com/science/article/pii/S0169809524002898

This paper likely explains why they are leveraging AI: https://alixsoliman.com/wp-content/uploads/2025/01/nature_deepmind-weather-ai_in-print_alix-soliman.pdf

The guidance still has the showers/light rain. Whether they're correct remains to be seen.

With the NHC now referring to Google DeepMind in some of its discussions, below is the latest Google DeepMind output for PTC9 at closest approach on the ensemble mean track:

My thoughts on what will become Imelda, while recognizing that there is still some uncertainty:

Courtesy of the Fujiwhara Effect, my thinking is that the stronger Humberto will pull what will become Imelda away from the coastline before U.S. landfall can occur and before ridging can rebuild overhead to break down the steering currents and later redirect Imelda toward U.S. landfall. The Bahamas and possibly Bermuda will need to closely monitor the developing tropical cyclone. There remains a degree of uncertainty.

Yes. That’s what the NWS reported.

153rd with a standard deviation of 9.16 degrees. Here's a comparison of 1983 with 2023 (which still ranks second through yesterday):

It was. Islip also tied its daily record of 85° from 1970.

Rainfall amounts in the New York City area were generally less than the 0.50"-1.50" forecast amounts. There was a stripe of heavier rainfall in parts of Connecticut. Storm total amounts included: Hartford: 1.72" Islip: 0.30" New Haven: 1.34" New York City-Central Park: 0.35" New York City-JFK Airport: 1.38" New York City-LaGuardia Airport: 0.33" Newark: 0.17" Storrs: 2.76" White Plains: 0.47" As a result, New York City is on track to finish with rainfall that is below the 4.31" monthly normal value for September. Almost as if to add insult to injury to the dry New York City area, in the past hour, Phoenix has picked up 1.09" of rain, along with winds gusting to 56 mph. The 1.11" so far today is its biggest rainstorm since October 13, 2018. Above normal temperatures will continue through the remainder of September. Another round of showers is possible Saturday night into Sunday. A significant rainfall is unlikely. The guidance and historical experience following a second half September mean temperature of 70° or above suggest that October will be warmer than normal in the New York City area. The two most recent Octobers with a cooler than normal first half like 2025 and a second half with a mean temperature of 70° or above were: 2017 (October mean temperature: 64.1° and October 2019: October mean temperature 59.9°). The extent of ridging to the north and interaction between the Humberto and Invest. 94 could ultimately determine whether Invest. 94 poses an eventual threat to a portion of the Southeast or stays out to sea. The potential Fujiwhara interaction would be unusual for the Atlantic basin. Typically, if the stronger system is to the right or east of the weaker one (possibly Invest. 94 as per most of the guidance at present), the stronger system will tend to deflect the weaker one northward and eastward sooner than might otherwise be the case. If both systems are of similar strength, they can rotate counterclockwise around a midpoint roughly between the centers of the two storms as they move along the steering flow. Two plausible scenarios are landfall along the South Carolina coast or a sharp turn out to sea after an approach toward the coastline. For now, tropics bear watching for the Southeast. The ENSO Region 1+2 anomaly was 0.0°C and the Region 3.4 anomaly was -0.4°C for the week centered around September 17. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.03°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. La Niña conditions will likely develop during mid- or late-autumn. The SOI was +9.81 today. The preliminary Arctic Oscillation (AO) was +1.341 today. Based on sensitivity analysis applied to the latest guidance, there is an implied near 86% probability that New York City will have a warmer than normal September (1991-2020 normal). September will likely finish with a mean temperature near 70.1° (0.9° above normal). Supplemental Information: The projected mean would be 2.1° above the 1981-2010 normal monthly value.

Newark has reached 86°. That's the fourth time it has reached 86° or above during the second half of September. The last time there were at least four such days during the second half of September was 2019 when there were five such days.

Westhampton reached 81° this afternoon. That broke the daily record of 80° from 1961.

The consistency has been remarkable. Smallest Mean Temperature Standard Deviation for September (through September 25th for 2025) for Central Park: 1. 1968 3.43° 2. 2025 3.75° (10th smallest difference between the mean temperatures for the first and second halves of September) 3. 1870 3.81° (6th smallest difference between the mean temperatures for the first and second halves of September) 4. 2024 3.94° 5. 1908 4.08°

Newark has reached 80 for the fourth consecutive day. The last time that happened after September 20th was October 1-4, 2023.

And the fact check on the political report aimed at reversing the EPA's endangerment finding. https://interactive.carbonbrief.org/doe-factcheck/images/Carbonbrief-DOE-factcheck.pdf

September 16-30, 2025 is well on track to record a mean temperature of 70.0° or above at Central Park. It would become the 12th such case since regular recordkeeping began in 1869. This warmth during the second half of September has often coincided with warmer than normal Octobers, both against the historic baseline and the 1991-2020 baseline. It has also typically been followed by warmer winters, particularly against the historic baseline. However, three of the four winters that followed such second half of September warmth since 2000 topped the 1991-2020 winter baseline. The coefficient of determination between the September 16-30 mean temperature and October and winter mean temperatures is exceptionally low (< 0.04), suggesting no predictive power when it comes to forecasting October and winter values. However, an alternative measure (ROC AUC) for addressing whether October and winter would be warmer/colder than specified values given a September 16-30 mean temperature shows stronger relationships, particularly for October. In general, ROC AUC is for problems where one wants a yes/no outcome and a probability (e.g., will winter be warmer than 36.2°?). ROC AUC Scores: October Outcome: Mean > 57.2°: 0.729 (moderately-strong) Mean > 57.9°: 0.714 (moderate) Mean of 60.0° or above: 0.625 Favored Range: 59.0°-60.0° December-February Outcome: Mean > 32.6°: 0.650 Mean > 36.2°: 0.667 Mean of 40.0° or above: 0.450 Favored Range: 37.5°-39.5° Note: 0.50 is no better than a random guess (no skill). Values < 0.50 include inverse outcomes at increasing skill for lower values. The latest CFSv2 shows a warmer than normal winter for the New York City area: Key Limitations: 1. Sample size is small 2. Mean anomalies do not exclude variability 3. Skill is modest (statistical and model) 4. Outcomes shown do not assess snowfall prospects, but all 11 prior cases saw 20" or more seasonal snowfall.

The landscape was comprised of savannas, wetlands, and woodlands. Tundra and Taiga were greatly reduced. Greenland's ice sheet was much smaller. The fauna of the period included both familiar and extinct animals. Early ancestors of modern elephants, giraffes, antelopes, along saber-toothed cats and short-faced hyenas were present. Giant ground sloths, camels, and early horses were present in North America Megalodon sharks rule the seas. Whales were evolving into today's forms. Early hominins emerged in Africa. Yes, at the current level of consumption, humanity is on an unsustainable path. The concept of "Earth Overshoot Day" captures a current reality where humanity is consuming more resources each year than what the world can provide. Add pollution (unrestrained greenhouse gas-led geoengineering, plastics/microplastics, a range of chemicals and derivatives) into the mix and that further illustrates unsustainability.