June 2025 discussion-obs: Summerlike

[FPizz]

1 minute ago, Brian5671 said:

crazy training cells in S NJ and DE right along the front

Yeah, hard for anyone to notice with the 3 guys bouncing posts off each other like its their job that has zero to do with obs. 

[LibertyBell]

Just now, TheClimateChanger said:

1954 had at least a brief shot of extreme heat as well, but maybe it didn't reach all the way to the coast. I know Ohio and western Pennsylvania had 99-100+ temperatures widespread on the 14th. Typically, the coastal Plain is several degrees (3-6F) warmer during hot spells.

It did I think 1954 hit 100+ in NYC twice.  Back then with the drier climate it was much easier to reach 100+  It was also easier to be colder.  On the coast, extremes have a lot to do with how much moisture is in the air.

[LibertyBell]

1 hour ago, TheClimateChanger said:

Looks like a mostly pleasant summer outside of a 5-day heatwave in late August, which, to be honest, was probably urban heat island related anyways. Isn't that the usual explanation for heat extremes these days? Certainly, seems suspect that the Central Park readings went from among the highest in the CWA to among the lowest in the recent heat wave.

In 1948, the first 24 days of August, prior to the heat wave, were pleasantly cool. The mean temperature for that stretch being 72.5F, which has been surpassed on the cool side only three times since (1962, 1992, and 2000).  The average high temperature, a chilly 79.2F. High temperatures that have only been seen once for that period since (2000). A true summer of yesteryear.

Can't downplay the extreme devastation caused by this heatwave.

AI Overview

 

The summer of 1948 included a notable heat wave, particularly in late August. While not as severe as the 1936 heat wave, it caused significant heat-related deaths and disruptions, especially in urban areas. In New York City, the heat wave resulted in over 1,000 excess deaths, according to the Boston Review. 

 

Here's a more detailed look:

• Timing and Severity:

  The August 1948 heat wave was particularly intense, exceeding the severity of a heat wave eleven years earlier. 

   
• Impact in New York City:

  The heat wave caused over 1,000 excess deaths in the city. 

   
• Disruptions:

  The heat wave led to widespread power outages, strained infrastructure, and impacted daily life for many, according to The New York Times. 

   
• Historical Context:

  While the 1936 heat wave remains the most severe in terms of widespread impact and duration, the 1948 heat wave serves as a reminder of the vulnerability of urban populations to extreme heat and the need for preparedness. 

   
• Specific Examples:

  In one instance, a delegation had to arrange for city water after a school providing water access closed, and the Bronx Zoo reported significantly lower attendance than on a typical summer Sunday. 

   
• Drownings and Heat Prostration:

  The heat wave was also marked by drownings and deaths due to heat prostration. 

[LibertyBell]

6 minutes ago, TheClimateChanger said:

1954 had at least a brief shot of extreme heat as well, but maybe it didn't reach all the way to the coast. I know Ohio and western Pennsylvania had 99-100+ temperatures widespread on the 14th. Typically, the coastal Plain is several degrees (3-6F) warmer during hot spells, but maybe the air mass petered out. I believe those heat waves were enhanced by drought in the middle of the country as well, similar but not as extreme as the 1930s drought.

this is an interesting article, it puts extreme heatwaves into a historical perspective, they talk about the lengthy 1980 and 1983 heatwaves which were 2 month heatwaves for a large part of the country, as well as the 1948 and 1966 historic heatwaves

 

https://www.bostonreview.net/articles/heat-death/

[LibertyBell]

2 minutes ago, LibertyBell said:

this is an interesting article, it puts extreme heatwaves into a historical perspective, they talk about the lengthy 1980 and 1983 heatwaves which were 2 month heatwaves for a large part of the country, as well as the 1948 and 1966 historic heatwaves

 

https://www.bostonreview.net/articles/heat-death/

https://www.nytimes.com/2025/06/24/nyregion/nyc-heat-wave.html

This article from 2 days ago also mentions the August 1948 heatwave and compares it to what just happened but it's paywalled =\

[LibertyBell]

9 minutes ago, TheClimateChanger said:

1954 had at least a brief shot of extreme heat as well, but maybe it didn't reach all the way to the coast. I know Ohio and western Pennsylvania had 99-100+ temperatures widespread on the 14th. Typically, the coastal Plain is several degrees (3-6F) warmer during hot spells, but maybe the air mass petered out. I believe those heat waves were enhanced by drought in the middle of the country as well, similar but not as extreme as the 1930s drought.

yes most of those earlier years heatwaves were drought driven, with less moisture in the air back then, the temperatures were cooler at night but when a hot airmass was around it was easier to get to triple digits.  Summer 1966 being a case in point, the driest year on record in NYC and the only one in which 100 degrees was reached during three different heatwaves and a total of four times.  1953 was another very dry year and the only other one in which NYC had 4 100+ degree days.

Have a look at this chart

 

https://www.weather.gov/okx/100degreedays

 

[Stormlover74]

76 and mostly sunny

[Roger Smith]

There was a considerable urban heat island in 1948, actually, you could rate it as 60 to 70 per cent of the present urban heat island. Perhaps most of its influence would be on overnight lows. But even by around 1890 to 1900 large cities were beginning to display an urban heat island. Vehicle traffic is only a small component of the cause of a heat island, the main components are altered surface albedos and escape of building heat. People were heating their houses before they had cars. Also they had transformed the urban environments to allow horse and carriage movement (thus changing heat retention). The strength of an urban heat island falls off rapidly after the first 100,000 of population in an urban area is reached and begins for towns as small as 2,000 population based on extensive research by many climatologists. You'd perhaps be surprised how quickly an urban heat island develops and how slowly it increases once developed, if you hadn't done active research or read the literature.

For my Toronto data I estimated the urban heat island began in the 1881-1890 decade (rated at 0.1 C differential then) and I took an arbitrary 0.1 increase each decade to 1971-1980 (adding 1.0 then). For 1981-1990 and the past 35 years I estimated it had stabilized at 1.1 C (2.0 F) deg. For NYC data I have assumed the same pace of change except that I would expect an increase had already begun for 1869 to 1880 so if I had data as far back as Toronto's 1840 startup, I would start modifying 1861-1870 at 0.2 F or 0.1 C and adding that amount every decade so the stable period of 1981-2025 would be actually +1.3 C (+2.34 F) relative to what NYC might record in an unaltered "rural" state. 

Now some might instantly say, but NYC is in a megalopolis much larger than greater Toronto, would it not warm up even more? Perhaps, but as I said, past 100,000 the rate of increase is very slow and probably past 5 million it cannot increase because the environment is so substantially altered on a regional basis. The strength of the greater New York heat island is probably well over +1.5 F out into parts of west central NJ near the end of suburban sprawl. 

As to the urban park question and temperature reductions in hot weather, that probably washes out of data sets fairly quickly as there aren't all that many hot days and the nights in question remain more affected anyway. Urban heat islands tend to be something like 75% minimum boosts and 25% maximum boosts, an estimate of a +2.0 heat island really means +1.0 for average maximum and +3.0 for average minimum. Large stretches of cloudy wet weather show very small urban heat island effects, dry and clear months would have larger differentials. 

[bluewave]

The NAM is finally getting replaced after they stop updating it in March 2017.

 

Public Information Statement 25-41

National Weather Service Headquarters Silver Spring, MD

845 AM EDT Thu Jun 26 2025

To: Subscribers:

-NOAA Weather Wire Service

-Emergency Managers Weather Information Network

-NOAAPORT

Other NWS Partners, Users and Employees

From: Richard Bandy

Acting Director

NCEP/Environmental Modeling Center

Subject: Soliciting Comments on Proposed Discontinuation of the North

American Mesoscale (NAM) model and other Regional Modeling Systems to be

Replaced by the Rapid Refresh Forecast System (RRFS) through July 26,

2025.

The Environmental Modeling Center (EMC) at the National Centers for

Environmental Prediction (NCEP) is working towards replacing the North

American Mesoscale (NAM) model, the High Resolution Window (HiresW) aside

from the Guam domain, the High Resolution Ensemble Forecast (HREF) and

the North American Rapid Refresh Ensemble (NARRE) systems with the

implementation of the Rapid Refresh Forecast System (RRFS) in early 2026.

The NWS is seeking comments on this proposed change through July 26,

2025.

This transition to RRFS would provide an hourly updating modeling system

over a North America region at 3 km horizontal grid spacing, which,

combined with the model retirements, would greatly unify and simplify the

“convective scale” (approximately 3 km grid spacing) regional models

within the NWS operational modeling suite.

As a deterministic system running to 84 h, the RRFS would fully retire

the NAM, and nearly fully retire the HiresW (aside from the Guam domain).

As an ensemble forecast system, the RRFS Ensemble Forecast System (REFS)

would fully retire the HREF and NARRE systems.

The deterministic RRFS generates full domain output at 3 km grid spacing,

and subset grid output over the contiguous United States (CONUS) and

Alaska (AK) (at 3 km grid spacing), and Hawaii (HI) and Puerto Rico (PR)

(at 2.5 km grid spacing). The RRFS will also provide output from a

separate 1.5 km RRFS fire weather run, with output provided over a 5 x 5

degree rotated latitude longitude region. Details of the RRFS output

grids are available in

https://www.emc.ncep.noaa.gov/mmb/mpyle/rrfs_info/rrfs_grids.txt

Relative differences between RRFS output products and the proposed-to-be-

retired system products will be discussed individually by the modeling

[donsutherland1]

Tomorrow will be unseasonably cool. The mercury could struggle to reach 70° in New York City. It should rise into the lower 70s at Newark.

The chilly highs will challenge the record for lowest high temperatures two days after an 80° or above low at Central Park, JFK Airport, and Newark. The existing records are below:

Central Park: 71°, July 9, 1883
JFK Airport: 76°, July 23, 2019
Newark: 76°, July 23, 2019 

All of those readings followed lows of 80° two days earlier.

Central Park has had 72 lows of 80° or above; Newark has had 50; and, JFK Airport has had 16.

Temperatures will return mainly to the lower 80s for the remainder of June. Excessive heat does not appear likely to return in the near-term.

The ENSO Region 1+2 anomaly was +1.0°C and the Region 3.4 anomaly was 0.2°C for the week centered around June 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.47°C and the ENSO Region 3.4 anomaly has averaged -0.03°C. Neutral ENSO conditions will likely continue through at least late summer.

The SOI was +12.65 yesterday. 

The preliminary Arctic Oscillation (AO) was +1.073 today. 

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 June (1991-2020 normal). June will likely finish with a mean temperature near 73.1° (1.1° above normal). 

 

[Sundog]

43 minutes ago, Roger Smith said:

There was a considerable urban heat island in 1948, actually, you could rate it as 60 to 70 per cent of the present urban heat island. Perhaps most of its influence would be on overnight lows. But even by around 1890 to 1900 large cities were beginning to display an urban heat island. Vehicle traffic is only a small component of the cause of a heat island, the main components are altered surface albedos and escape of building heat. People were heating their houses before they had cars. Also they had transformed the urban environments to allow horse and carriage movement (thus changing heat retention). The strength of an urban heat island falls off rapidly after the first 100,000 of population in an urban area is reached and begins for towns as small as 2,000 population based on extensive research by many climatologists. You'd perhaps be surprised how quickly an urban heat island develops and how slowly it increases once developed, if you hadn't done active research or read the literature.

For my Toronto data I estimated the urban heat island began in the 1881-1890 decade (rated at 0.1 C differential then) and I took an arbitrary 0.1 increase each decade to 1971-1980 (adding 1.0 then). For 1981-1990 and the past 35 years I estimated it had stabilized at 1.1 C (2.0 F) deg. For NYC data I have assumed the same pace of change except that I would expect an increase had already begun for 1869 to 1880 so if I had data as far back as Toronto's 1840 startup, I would start modifying 1861-1870 at 0.2 F or 0.1 C and adding that amount every decade so the stable period of 1981-2025 would be actually +1.3 C (+2.34 F) relative to what NYC might record in an unaltered "rural" state. 

Now some might instantly say, but NYC is in a megalopolis much larger than greater Toronto, would it not warm up even more? Perhaps, but as I said, past 100,000 the rate of increase is very slow and probably past 5 million it cannot increase because the environment is so substantially altered on a regional basis. The strength of the greater New York heat island is probably well over +1.5 F out into parts of west central NJ near the end of suburban sprawl. 

As to the urban park question and temperature reductions in hot weather, that probably washes out of data sets fairly quickly as there aren't all that many hot days and the nights in question remain more affected anyway. Urban heat islands tend to be something like 75% minimum boosts and 25% maximum boosts, an estimate of a +2.0 heat island really means +1.0 for average maximum and +3.0 for average minimum. Large stretches of cloudy wet weather show very small urban heat island effects, dry and clear months would have larger differentials. 

Growing up and spending summers in Greece I would visit my grandparents that lived JUST outside a small town (population ~5,000.) At the edge of the village/town it would turn into fields of open land and about 500 meters into the fields was my grandparents' home. 

Walking back from the town at night toward the house I could EASILY feel the temperature drop by several degrees once I would get to the edge. It was like walking into an air conditioned room. 

So I have first hand experience of a village or small town causing an obvious UHI even though people think a population center that small would be too insignificant to cause such an effect. 

[LibertyBell]

12 minutes ago, donsutherland1 said:

Tomorrow will be unseasonably cool. The mercury could struggle to reach 70° in New York City. It should rise into the lower 70s at Newark.

The chilly highs will challenge the record for lowest high temperatures two days after an 80° or above low at Central Park, JFK Airport, and Newark. The existing records are below:

Central Park: 71°, July 9, 1883
JFK Airport: 76°, July 23, 2019
Newark: 76°, July 23, 2019 

All of those readings followed lows of 80° two days earlier.

Central Park has had 72 lows of 80° or above; Newark has had 50; and, JFK Airport has had 16.

Temperatures will return mainly to the lower 80s for the remainder of June. Excessive heat does not appear likely to return in the near-term.

The ENSO Region 1+2 anomaly was +1.0°C and the Region 3.4 anomaly was 0.2°C for the week centered around June 18. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.47°C and the ENSO Region 3.4 anomaly has averaged -0.03°C. Neutral ENSO conditions will likely continue through at least late summer.

The SOI was +12.65 yesterday. 

The preliminary Arctic Oscillation (AO) was +1.073 today. 

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 June (1991-2020 normal). June will likely finish with a mean temperature near 73.1° (1.1° above normal). 

 

JFK Airport: 76°, July 23, 2019

 

Don was this after JFK's back to back 99 degree highs when they set a new heat index record??

[LibertyBell]

13 minutes ago, Sundog said:

Growing up and spending summers in Greece I would visit my grandparents that lived JUST outside a small town (population ~5,000.) At the edge of the village/town it would turn into fields of open land and about 500 meters into the fields was my grandparents' home. 

Walking back from the town at night toward the house I could EASILY feel the temperature drop by several degrees once I would get to the edge. It was like walking into an air conditioned room. 

So I have first hand experience of a village or small town causing an obvious UHI even though people think a population center that small would be too insignificant to cause such an effect. 

People need to stop creating concrete jungles, not only is it cooler outside of the city, it's also less polluted and much easier to sleep at night and breathe clean air with far lower rates of asthma.

[donsutherland1]

1 minute ago, LibertyBell said:

JFK Airport: 76°, July 23, 2019

 

Don was this after JFK's back to back 99 degree highs when they set a new heat index record??

Yes.

[bluewave]

1 hour ago, Roger Smith said:

But even by around 1890 to 1900 large cities were beginning to display an urban heat island.

Manhattan UHI peaked in 1910 right before the population density began to decline.

 

 

[winterwx21]

2 hours ago, Stormlover74 said:

76 and mostly sunny

It did touch 80 very briefly here this afternoon when the sun came out, but then dropped back to the mid 70s quickly due to the east wind. 73 right now. That east wind felt very refreshing when I was out running. 

[Stormlover74]

32 minutes ago, winterwx21 said:

It did touch 80 very briefly here this afternoon when the sun came out, but then dropped back to the mid 70s quickly due to the east wind. 73 right now. That east wind felt very refreshing when I was out running. 

Yeah the sunny skies didn't last long. Feels refreshing now at 71

[steve392]

Winds really starting to howl at home. Temp at 69....hehehe alrighttttttttt

[SACRUS]

 

69 / 57 

[ForestHillWx]

63/57…opening windows. 

[Snowlover11]

Beautiful outside

66F with a slight breeze.

[Wxoutlooksblog]

My 5th floor apartment in Douglaston facing west with open sky got so hot with the westward facing wall of the building and now an easterly wind I am running my a/c full blast to try to fully get the heat out. I ran it all night last night and probably will need to run it over night another night to finally get it comfortably cool. Then it warms up with plenty of humidity on Saturday. Unless we sneak a 90 in on Saturday, Sunday, Monday or Tuesday (and it's unlikely since winds will be out of the s-sw) I do not think we see another 90+ day in NYC until the second or more likely the third week of July.

WX/PT

[nycwinter]

62 at almost 5:00 am i could actually go out and wear a hoodie this morning..

[bluewave]

Continuation of the same pattern into late June. Another weekend with chances for rain but no washout. Saturday looks like the best chance for scattered convection. Drier on Sunday. Then mid 90s on Monday just inland from sea breeze front west of NYC. 

 

[LoboLeader1]

Currently 55 up here in the Berks, 63 back in HPN. I would take this over heat & humidity in a heartbeat.

[gravitylover]

Nice little round of moderately heavy rain passing thru. 

[IrishRob17]

16 hours ago, LibertyBell said:

No urban heat island in 1948..... 

Yeah in 1948, concrete and asphalt wasn’t invented yet and NYC was nothing but rounded up prairie schooner wagons and teepees sprawled across all the open fields…c’mon man!

2 hours ago, nycwinter said:

62 at almost 5:00 am i could actually go out and wear a hoodie this morning..

61 here this morning with .05 overnight, cooler than recent mornings. I love me some hoodie season…..this ain’t it. 

[LongBeachSurfFreak]

15 hours ago, LibertyBell said:

People need to stop creating concrete jungles, not only is it cooler outside of the city, it's also less polluted and much easier to sleep at night and breathe clean air with far lower rates of asthma.

So we should abandon cities and destroy rural areas and turn them into endless suburbs. 
The reality from the perspective of the planet is the EXACT OPPOSITE. We want more people in tightly packed cities and less McMansions on quarter acre lots. Upstate NY reforesting over the last century is a great example of what we want to see. 

[MJO812]

1 minute ago, LongBeachSurfFreak said:

So we should abandon cities and destroy rural areas and turn them into endless suburbs. 
The reality from the perspective of the planet is the EXACT OPPOSITE. We want more people in tightly packed cities and less McMansions on quarter acre lots. Upstate NY reforesting over the last century is a great example of what we want to see. 

We need less buildings  like upstate NY.

[Sundog]

6 minutes ago, LongBeachSurfFreak said:

So we should abandon cities and destroy rural areas and turn them into endless suburbs. 
The reality from the perspective of the planet is the EXACT OPPOSITE. We want more people in tightly packed cities and less McMansions on quarter acre lots. Upstate NY reforesting over the last century is a great example of what we want to see. 

What sucks is living on top each other is not healthy. People underestimate the psychological damage constant noise does to a human for example. 

Air pollution will be worse no matter how "clean" a city gets compared to suburbs/rural. 

For people, I think overall it's much better to live on that half acre lot than living like an ant colony. 

For the planet obviously it's better if people concentrated in as few urban centers as possible and left everything around alone.