donsutherland1

That’s been a persistent theme. It may have something to do with the exceptionally warm SSTs off the northeastern U.S. and eastern Canada.

Brilliant sunshine provided for another unseasonably warm October day. Temperatures soared well into the 70s across the region. Newark reached 70° for the 173rd time this year. That tied the record set in 2010. Four of the five years that saw 170 or more such days have occurred since 2000 and three have occurred since 2010. Tomorrow will be a bit cooler but still unseasonably warm. A more seasonably cool weekend lies ahead. Early next week and again later in the week, storms could bring a moderate to significant rainfall to parts of the region. No sharp cold shots appear likely through the remainder of October. The following locations are on course to challenge or establish new record high lowest monthly temperatures for October (through October 20): Allentown: 40° (record: 38°, 1971) Boston: 46° (record: 45°, 1971) Bridgeport: 43° (record: 41°, 2004) Islip: 42° (record: 40°, 1971 and 2017) New York City-JFK: 48° (record: 46°, 1971) New York City-LGA: 51° (record: 47°, 1971) New York City-NYC: 47° (record: 45°, 1971) Newark: 46° (record: 45°, 1971) Philadelphia: 46° (record: 45°, 1882, 1927 and 1931) Poughkeepsie: 38° (record: 35°, 1971, 1995 and 1996) White Plains: 44° (record: 40°, 1971) In northern Maine, Caribou has yet to experience its first freeze of autumn. The prior record latest first freeze occurred on October 17, 1970. The normal first freeze (1991-2020) occurs on September 25th, which was an increase of 2 days over the prior 1981-2010 base period. The MJO has now completed its passage through Phase 5 at a very high amplitude. During the 1991-2020 period, there were 6 cases with passage through Phase 5 with at least three days at an amplitude of 1.500 or above: 1998, 2000, 2004, 2010, 2017, and 2020. There was a strong signal for the second half of October to wind up warmer than normal (83%) cases in the New York City area. However, that signal broke down to a 50-50 split for the first 10 days of November. That hints at possible timing for a pattern transition depending on the pattern evolution and changes in the teleconnections. Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27". Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.8°C for the week centered around October 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.15°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. La Niña conditions will likely persist through at least mid-winter. The SOI was +12.18 today. The preliminary Arctic Oscillation (AO) figure was +0.619 today. On October 19 the MJO was in Phase 2 at an amplitude of 0.334 (RMM). The October 18-adjusted amplitude was 0.312 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 99% probability that New York City will have a warmer than normal October (1991-2020 normal). October will likely finish with a mean temperature near 61.8° (3.9° above normal).

Ironically, much of the region is competing with 1971 for the highest October minimum temperature.

Today will probably be a few degrees cooler.

Morning thoughts… It will partly to mostly sunny and unseasonably warm. High temperatures will likely reach the middle and upper 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 74° Newark: 79° Philadelphia: 77° Normals: New York City: 30-Year: 62.6°; 15-Year: 63.2° Newark: 30-Year: 64.1°; 15-Year: 65.0° Philadelphia: 30-Year: 65.3°; 15-Year: 65.7° The warm weather will continue through tomorrow, but a cooler weekend lies ahead.

Under bright sunshine, the temperature surged into the middle and upper 70s across much of the region. High temperatures included: Bridgeport: 77° (old record: 75°, 1953) Islip: 75° (old record: 74°, 1969, 1979, and 1984) New Haven: 77° (old record: 73°, 1953 and 2017) New York City-JFK: 79° New York City-LGA: 80° (old record: 79°, 1953 and 1984) New York City-NYC: 75° Newark: 80° (tied record set in 1947 and tied in 1969) Philadelphia: 76° White Plains: 74° Newark reached 70° for the 172nd time this year. As a result, 2021 is now has the 2nd most days on record. Today was also Newark's 116th 80° day, which ranks 2nd on the all-time list. Tomorrow and Friday will be unseasonably warm. Another cool shot is likely for the weekend. The MJO has now completed its passage through Phase 5 at a very high amplitude. During the 1991-2020 period, there were 6 cases with passage through Phase 5 with at least three days at an amplitude of 1.500 or above: 1998, 2000, 2004, 2010, 2017, and 2020. There was a strong signal for the second half of October to wind up warmer than normal (83%) cases in the New York City area. However, that signal broke down to a 50-50 split for the first 10 days of November. That hints at possible timing for a pattern transition depending on the pattern evolution and changes in the teleconnections. Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27". Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.8°C for the week centered around October 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.15°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. La Niña conditions will likely persist through at least mid-winter. The SOI was +6.70 today. The preliminary Arctic Oscillation (AO) figure was +0.151 today. On October 18 the MJO was in Phase 2 at an amplitude of 0.315 (RMM). The October 17-adjusted amplitude was 0.375 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 98% probability that New York City will have a warmer than normal October (1991-2020 normal). October will likely finish with a mean temperature near 61.7° (3.8° above normal).

Bridgeport and New Haven have also set new records. LGA has tied its record.

Morning thoughts… It will partly to mostly sunny and unseasonably warm. High temperatures will likely reach the middle and upper 70s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 76° Newark: 80° Philadelphia: 78° Normals: New York City: 30-Year: 62.9°; 15-Year: 63.6° Newark: 30-Year: 64.4°; 15-Year: 65.4° Philadelphia: 30-Year: 65.6°; 15-Year: 66.1° The warm weather will continue through Friday.

After a chilly start, temperatures moderated under strong sunshine. Highs generally reached the middle and upper 60s across the region. Newark reached 70° for the 171st time this year. As a result, 2021 is now tied with 1985 and 2015 for the 2nd most days on record. Warmer air will return tomorrow. Tomorrow through Friday will be unseasonably warm. Another cool shot is likely for the weekend. The MJO has now completed its passage through Phase 5 at a very high amplitude. During the 1991-2020 period, there were 6 cases with passage through Phase 5 with at least three days at an amplitude of 1.500 or above: 1998, 2000, 2004, 2010, 2017, and 2020. There was a strong signal for the second half of October to wind up warmer than normal (83%) cases in the New York City area. However, that signal broke down to a 50-50 split for the first 10 days of November. That hints at possible timing for a pattern transition depending on the pattern evolution and changes in the teleconnections. Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27". Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.8°C for the week centered around October 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.15°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. La Niña conditions will likely persist through at least mid-winter. The SOI was +15.47 today. The preliminary Arctic Oscillation (AO) figure was -0.595 today. On October 17 the MJO was in Phase 5 at an amplitude of 0.374 (RMM). The October 16-adjusted amplitude was 0.594 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 96% probability that New York City will have a warmer than normal October (1991-2020 normal). October will likely finish with a mean temperature near 61.6° (3.7° above normal).

The sample size is really small. 1970-71 and 1973-74 were fairly cold, but not severely cold.

I didn’t see that in your comment. I’ll look into such winters and post what I find.

October-November had mean temperatures of a half standard deviation or more above normal as recently as 2014 and a very cold winter (2014-15) followed.

Yes. 48.

Through October 18, Central Park has had a mean temperature of 64.6° (11th warmest). However, October 2021 would rank among the top 3 warmest starts to October without Central Park's trees issue. https://www.americanwx.com/bb/topic/55633-october-2021/?do=findComment&comment=6145116 Using the regression equation noted in the linked post, the figure would be approximately 67.4° (3rd warmest) without the trees issue. Using the shorter 1948-2021 period, which reflects the period of record for numerous local stations, it would rank 2nd. A ranking of 3rd would be in line with what has occurred around the region. Regional Ranking for Select Stations Record Length of 50 Years or More) and start of record: Albany: 4th (1874) Bridgeport: 5th (1948) Islip: 3rd (1963) New Brunswick: Tied 6th (1893) New Haven: 1st (1948) New York City-JFK: 4th (1948) New York City-LGA: 5th (1939) Newark: 2nd (1931) Philadelphia: Tied 5th (1873) Poughkeepsie: 2nd (1931) White Plains: 6th (1948) The biggest issue concerns artificially low maximum temperatures. The October 1-18 average high temperature at Central Park has been 70.3°. That is lower than the averages at both JFK Airport and LaGuardia Airport. In addition, on 16 of the 18 days (89%), Central Park registered the lowest maximum temperature or was tied with the lowest maximum temperature. In sum, the neglect of the trees issue at Central Park is impairing the integrity of the climate record when the trees are leafed out.

An amazing rainbow.

Morning thoughts… It will partly to mostly sunny and milder today. High temperatures will likely reach the middle and upper 60s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 65° Newark: 71° Philadelphia: 69° Normals: New York City: 30-Year: 63.3°; 15-Year: 64.0° Newark: 30-Year: 64.8°; 15-Year: 65.8° Philadelphia: 30-Year: 66.0°; 15-Year: 66.6° It will turn noticeably milder tomorrow.

At 10:54 pm, the temperature at Boston had fallen to 49 degrees. That is the latest first 40s temperature on record. The old record was October 13, 2018. 6 of the 15 cases where the first such reading occurred October 1 or later have occurred since 2010. 4 of the last 5 years have seen the first 40s occur on October 1 or later. The mean first date has increased as follows during the last three base periods: 1971-00: September 18; 1981-10: September 19: 1991-20: September 23. Records go back to 1872.

Yes. The high was 64.

I have never seen more than two.

JFK had a low of 50 so far. It should be in the 40s tonight.

Today was the coolest day so far this season. New York City and Philadelphia recorded low temperatures in the 40s for the first time this season. Tomorrow will be another cool day. After perhaps the coldest readings so far this season, the mercury will reach the lower and middle 60s across the area. Warmer air will return Wednesday. Another cool shot is likely for the weekend. Elsewhere, Bismarck recorded its 154th 70° day. That broke the annual record of 153 days, which had been set in 2016. Caribou has yet to record its first freeze of the season. The previous latest first freeze occurred on October 17, 1970. The MJO has now completed its passage through Phase 5 at a very high amplitude. During the 1991-2020 period, there were 6 cases with passage through Phase 5 with at least three days at an amplitude of 1.500 or above: 1998, 2000, 2004, 2010, 2017, and 2020. There was a strong signal for the second half of October to wind up warmer than normal (83%) cases in the New York City area. However, that signal broke down to a 50-50 split for the first 10 days of November. That hints at possible timing for a pattern transition depending on the pattern evolution and changes in the teleconnections. Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27". Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. The ENSO Region 1+2 anomaly was -0.2°C and the Region 3.4 anomaly was -0.8°C for the week centered around October 13. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.15°C and the ENSO Region 3.4 anomaly has averaged -0.43°C. La Niña conditions will likely persist through at least mid-winter. The SOI was +19.66 today. The preliminary Arctic Oscillation (AO) figure was -1.464 today. On October 16 the MJO was in Phase 6 at an amplitude of 0.589 (RMM). The October 15-adjusted amplitude was 0.967 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 93% probability that New York City will have a warmer than normal October (1991-2020 normal). October will likely finish with a mean temperature near 61.6° (3.7° above normal).

A heavier shower moving out over the Long Island Sound resulted in a rainbow.

Late morning with a distinct autumn “feel.”

Morning thoughts… This morning, the temperature fell below 50° for the first time this season in Central Park. That is the second latest first occurrence on record. Boston is still waiting for its first 40s of the season. The old record was October 13, 2008. It will partly to mostly sunny and cool today. High temperatures will likely reach the upper 50s and lower 60s in most of the region. Likely high temperatures around the region include: New York City (Central Park): 60° Newark: 64° Philadelphia: 63° Normals: New York City: 30-Year: 63.6°; 15-Year: 64.4° Newark: 30-Year: 65.2°; 15-Year: 66.2° Philadelphia: 30-Year: 66.4°; 15-Year: 67.0° Tomorrow will be another autumn-like day with readings mainly topping out in the lower 60s.

Tomorrow and Tuesday will be cool days. Nights will be mainly in the 40s and highs in the upper 50s and lower 60s. Warmer air will likely return by mid-week. Another cool shot is likely for the weekend. Out West, Bismarck reached 75°. That was the 153rd 70° or above day, which tied the record set in 2016. Boston is still awaiting its first temperature in the 40s. The previous latest first such occurrence was October 13, 2018. The MJO has now completed its passage through Phase 5 at a very high amplitude. During the 1991-2020 period, there were 6 cases with passage through Phase 5 with at least three days at an amplitude of 1.500 or above: 1998, 2000, 2004, 2010, 2017, and 2020. There was a strong signal for the second half of October to wind up warmer than normal (83%) cases in the New York City area. However, that signal broke down to a 50-50 split for the first 10 days of November. That hints at possible timing for a pattern transition depending on the pattern evolution and changes in the teleconnections. Fall 2021 will likely be wetter to much wetter than normal in the northern Middle Atlantic region. Since 1869, there have been 9 August cases where New York City picked up 20.00" or more rainfall during the summer. Two thirds of those cases (and 4/5 of those with summer mean temperatures of 73.0° or above) had 17.00" or more fall precipitation in New York City. 2011 is probably the closest match in terms of precipitation and a nearly identical summer mean temperature. Mean fall precipitation for those 9 cases was 14.86". The median was 17.35". The 1991-2020 normal value is 12.27". Following very wet July-September periods, winter (December-February) precipitation has typically been near or below normal. The most recent exception was winter 2018-19. La Niña conditions have now developed. The ENSO Region 1+2 anomaly was +0.1°C and the Region 3.4 anomaly was -0.7°C for the week centered around October 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.08°C and the ENSO Region 3.4 anomaly has averaged -0.35°C. La Niña conditions will likely persist through at least mid-winter. The SOI was +19.66 today. The preliminary Arctic Oscillation (AO) figure was -1.732 today. On October 15 the MJO was in Phase 6 at an amplitude of 0.966 (RMM). The October 14-adjusted amplitude was 1.417 (RMM). Based on sensitivity analysis applied to the latest guidance, there is an implied 90% probability that New York City will have a warmer than normal October (1991-2020 normal). October will likely finish with a mean temperature near 61.7° (3.8° above normal).