September 2025 OBS-Discussion centered NYC subforum

[Picard]

16 minutes ago, wdrag said:

Late yesterday (9/13/25) shower amounts via CoCoRaHs Click if in disbelief. 

It got quite threatening looking up here in the afternoon and evening yesterday.  Nothing, not even a drip.  Everything was well east.

[nycwinter]

real summery feel outside this morning i cant believe in mid sept we are still having days like this..

[Sundog]

1 minute ago, nycwinter said:

real summery feel outside this morning i cant believe in mid sept we are still having days like this..

It's not out of the ordinary. 

[anthonymm]

26 minutes ago, nycwinter said:

real summery feel outside this morning i cant believe in mid sept we are still having days like this..

Cold early September is a classic fake out. We don't truly shake summer off totally these days until like mid October.

[donsutherland1]

2 hours ago, wdrag said:

Late yesterday (9/13/25) shower amounts via CoCoRaHs Click if in disbelief. 

Despite the dry end to August, precipitation is running above normal in parts of the region through the first two weeks of September and much above the amount for last year in all areas. 2025 is September 1-13 precipitation, but none is expected today. While this does not ensure that the month will finish above normal, it is a welcome development.

 

[SnoSki14]

2 hours ago, nycwinter said:

real summery feel outside this morning i cant believe in mid sept we are still having days like this..

Where have you been the last 10+ years 

[SnoSki14]

2 hours ago, anthonymm said:

With no cool downs in sight September might average seasonable if not slightly above normal no? Much warmer looking nights ahead as well.

There's hints of a cool down for next weekend plus any coastal influence will keep highs down. 

No definitive fall like cool down yet though 

[MANDA]

1 hour ago, donsutherland1 said:

Despite the dry end to August, precipitation is running above normal in parts of the region through the first two weeks of September and much above the amount for last year in all areas. 2025 is September 1-13 precipitation, but none is expected today. While this does not ensure that the month will finish above normal, it is a welcome development.

 

Hi Don-

Can you do the same chart for Y.T.D. and 12 month rolling?  If not too much trouble.  I'd love to see what that looks like.

Thanks-

Mike

[donsutherland1]

9 minutes ago, MANDA said:

Hi Don-

Can you do the same chart for Y.T.D. and 12 month rolling?  If not too much trouble.  I'd love to see what that looks like.

Thanks-

Mike

Here you go:

 

[MANDA]

1 hour ago, donsutherland1 said:

Here you go:

 

Thanks Don.  That's kind of what I was expecting it to look like.  My perception was that it has been a drier than normal year to date and drier than 2024 and a much drier 12 month period compared to normal and 2024.  It has just been dry.  Barring any tropical activity for the second half of this month September I think will finish drier than normal.  Not going to be much rainfall over this sub forum for the coming week.

[Roger Smith]

Some details about evolution of the Great Atlantic Hurricane weather pattern. Aug 1944 had been very hot in the east, and this continued into early September. In fact NYC set a record 97F on Sep 2nd that was later erased by the 102F in 1953. It was 94F on the 3rd and 90F on the 5th. No measurable rain fell from Aug 23 to Sep 11 (a 20 day dry spell) ...

Cooler air masses arrived thereafter and were in place when the G.A.H. ran up the east coast. A very warm day followed the passage of the core offshore, in strong southwest to west winds on Sep 15th as shown below ...

NYC obs Sep 12 to 18 1944

Date ___ Max _ Min __ rain

09 12 ___ 72 __ 63 ___ 1.64

09 13 ___ 74 __ 66 ___ 3.94

09 14 ___ 78 __ 65 ___ 3.82

09 15 ___ 86 __ 70 ___ Tr

09 16 ___ 84 __ 66 ___ 0.00

09 17 ___ 80 __ 63 ___ 0.00

09 18 ___ 73 __ 63 ___ 0.00

09 19 ___ 69 __ 64 ___ 0.09

Weather maps show the G.A.H. at these locations:

Sep 13 1944 n.e Bahamas

Sep 14 1944 near C Hatteras 12z to s.e. Long Island

Sep 15 1944 across Cape Cod into Bay of Fundy (rapidly weakening to TS)

Sep 16 1944 absorbed by northern low near e Nfld

The 9.40" of rain that fell Sep 12-14 represented 90% of the month's rain (0.77" fell on 28th), and another 14 day dry spell followed Sep 29 to Oct 12 during which another record high was set (88F on Oct 7, 1944).

And they say climate change is making the weather more intense. S-u-u-re. 

[MANDA]

3 hours ago, donsutherland1 said:

Here you go:

 

Data at my location. 

Y.T.D. = 33.56"

12 month 9/14/24 - 9/14/25  = 43.01"

Wetter than all of the above climo stations.

[Sundog]

26 minutes ago, Roger Smith said:

Some details about evolution of the Great Atlantic Hurricane weather pattern. Aug 1944 had been very hot in the east, and this continued into early September. In fact NYC set a record 97F on Sep 2nd that was later erased by the 102F in 1953. It was 94F on the 3rd and 90F on the 5th. No measurable rain fell from Aug 23 to Sep 11 (a 20 day dry spell) ...

Cooler air masses arrived thereafter and were in place when the G.A.H. ran up the east coast. A very warm day followed the passage of the core offshore, in strong southwest to west winds on Sep 15th as shown below ...

NYC obs Sep 12 to 18 1944

Date ___ Max _ Min __ rain

09 12 ___ 72 __ 63 ___ 1.64

09 13 ___ 74 __ 66 ___ 3.94

09 14 ___ 78 __ 65 ___ 3.82

09 15 ___ 86 __ 70 ___ Tr

09 16 ___ 84 __ 66 ___ 0.00

09 17 ___ 80 __ 63 ___ 0.00

09 18 ___ 73 __ 63 ___ 0.00

09 19 ___ 69 __ 64 ___ 0.09

Weather maps show the G.A.H. at these locations:

Sep 13 1944 n.e Bahamas

Sep 14 1944 near C Hatteras 12z to s.e. Long Island

Sep 15 1944 across Cape Cod into Bay of Fundy (rapidly weakening to TS)

Sep 16 1944 absorbed by northern low near e Nfld

The 9.40" of rain that fell Sep 12-14 represented 90% of the month's rain (0.77" fell on 28th), and another 14 day dry spell followed Sep 29 to Oct 12 during which another record high was set (88F on Oct 7, 1944).

And they say climate change is making the weather more intense. S-u-u-re. 

The potential is there for more intense systems. Theres a straightforward relationship between energy and intensity. 

That doesn't mean that intensity will be realized or there won't be other factors that hamper the realization of that intensity.  

[donsutherland1]

Temperatures will top out in the upper 70s to perhaps lower 80s tomorrow and then the lower to middle 70s on Tuesday and Wednesday. Readings will likely return to the upper 70s on Thursday and the lower 80s on Friday. Cooler air should return for the weekend.

In terms of near-term precipitation, a cutoff system near the Delmarva could bring some showers or a period of rain on Wednesday into Thursday. Parts of the Delmarva and Jersey Shore will likely see the heaviest amounts.

September 1-15 remains on track to achieve a solid cool anomaly. Since 2000, there have been nine years that saw a cooler than normal first half of September. Two-thirds of those years went on to record a warmer than normal second half of September. Only two of those years (2017 and 2019) wound up with a monthly mean temperature of 70.0° or above. Overall, for two-thirds of those years, the cool start was sufficiently cool to produce a cooler than normal monthly anomaly. The last year that saw both a cooler than normal first half and second half of September was 2009. Prior to that, it was 2001. The last year to record a cooler than normal first half of September followed by a warmer than normal September was 2024.

The ENSO Region 1+2 anomaly was -0.3°C and the Region 3.4 anomaly was -0.4°C for the week centered around August 27. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.33°C and the ENSO Region 3.4 anomaly has averaged -0.32°C. La Niña conditions will likely develop during mid- or late-autumn.

The SOI was -9.21 yesterday. 

The preliminary Arctic Oscillation (AO) was -0.079 today. 

Based on sensitivity analysis applied to the latest guidance, there is an implied near 56% probability that New York City will have a cooler than normal September (1991-2020 normal). September will likely finish with a mean temperature near 68.9° (0.3° below normal). 

Supplemental Information: The projected mean would be 0.9° above the 1981-2010 normal monthly value.

 

[Roger Smith]

Potential is one thing but reality seems to be global blanding at least in the mid-latitudes. I can't remember as much boring weather as we've seen in the past five years. To my way of thinking, adding extra cloud, moisture and heat to all air masses is a recipe for less rather than more cyclogenesis. Everywhere is becoming Vladivostok. 

[steve392]

78 and partly cloudy. Seems like a nice day if i were to get outside.

[winterwarlock]

84 back to back highs

 

10 of 14 days with 80 plus highs in September...summery and more to come

[steve392]

23 minutes ago, winterwarlock said:

84 back to back highs

 

10 of 14 days with 80 plus highs in September...summery and more to come

Any significant rain the rest of the month?