July 2025 Discussion-OBS - seasonable summer variability

[TheClimateChanger]

Just now, TheClimateChanger said:

Wow, since 1970, July nighttime low temperatures at NYC have risen 3.1F, while lows at Charlotteburg Reservoir have risen 7.1F, per linear regression.

You can even see the point where atmospheric changes start to swamp out the UHI signal. From 1970-2000, both sites show a small cooling trend, with NYC lows dropping 0.2F, while the Charlotteburg site saw lows drop by 0.7F during that timeframe. Hard to tell if the late 20th century cooling is a real trend or just an artifact from changing equipment/observation practices and site location. I'm not sure if that cooling trend is real or just manufactured by those non-climatic factors.

[LibertyBell]

13 minutes ago, TheClimateChanger said:

You can even see the point where atmospheric changes start to swamp out the UHI signal. From 1970-2000, both sites show a small cooling trend, with NYC lows dropping 0.2F, while the Charlotteburg site saw lows drop by 0.7F during that timeframe. Hard to tell if the late 20th century cooling is a real trend or just an artifact from changing equipment/observation practices and site location. I'm not sure if that cooling trend is real or just manufactured by those non-climatic factors.

it's not really cooling, maxes have stabilized while mins are climbing so overall it's still warming.

 

[TheClimateChanger]

10 minutes ago, LibertyBell said:

it's not really cooling, maxes have stabilized while mins are climbing so overall it's still warming.

 

Wow, I don't agree with this statement at all. Recent Julys have had mean minimum temperatures that are warmer than the mean 24-hour averages from past "cold" Julys. Probably after 2050, we will begin to see Julys where the mean minimum temperatures exceed the mean maximum temperatures from old-school cold Julys. For some reason, you only ever look and compare to the hottest years?

For example, JFK's mean minimum last month was 72.7F. That exceeds the mean 24-hour average of 71.8F in 1956, 72.2F in 1996, 72.2F in 1965, 72.3F in 2000, 72.4F in 2001, and falls just shy of the 72.8F observed in 1976. It's probably just a handful of decades before JFK starts seeing low temperatures in July that exceed the mean maximum temperatures observed in cold Julys (e.g., 1956, 77.9F; 1996, 78.6F; 2000, 79.5F; and 1967, 79.7F). I don't think its too hard to imagine a future in 2060 where NYC looks more like Washington, DC of 2000-2020, where such low temperatures are common.

I think it's significant when low temperatures are exceeding the mean of high and low from many past years. In the first 6 years after installation of the ASOS at JFK, there were 3 years in which the month of July had a colder mean temperature than this year's mean low temperature (1996, 2000, and 2001).

[Sundog]

1 hour ago, TheClimateChanger said:

Wow, since 1970, July nighttime low temperatures at NYC have risen 3.1F, while lows at Charlotteburg Reservoir have risen 7.1F, per linear regression.

Well Charlotteburg is the biggest city in the country, after all. 

[LibertyBell]

1 hour ago, TheClimateChanger said:

Wow, I don't agree with this statement at all. Recent Julys have had mean minimum temperatures that are warmer than the mean 24-hour averages from past "cold" Julys. Probably after 2050, we will begin to see Julys where the mean minimum temperatures exceed the mean maximum temperatures from old-school cold Julys. For some reason, you only ever look and compare to the hottest years?

For example, JFK's mean minimum last month was 72.7F. That exceeds the mean 24-hour average of 71.8F in 1956, 72.2F in 1996, 72.2F in 1965, 72.3F in 2000, 72.4F in 2001, and falls just shy of the 72.8F observed in 1976. It's probably just a handful of decades before JFK starts seeing low temperatures in July that exceed the mean maximum temperatures observed in cold Julys (e.g., 1956, 77.9F; 1996, 78.6F; 2000, 79.5F; and 1967, 79.7F). I don't think its too hard to imagine a future in 2060 where NYC looks more like Washington, DC of 2000-2020, where such low temperatures are common.

I think it's significant when low temperatures are exceeding the mean of high and low from many past years. In the first 6 years after installation of the ASOS at JFK, there were 3 years in which the month of July had a colder mean temperature than this year's mean low temperature (1996, 2000, and 2001).

I think you misread what I wrote: what you stated here is what I said, the mins are rapidly increasing, the maxes are not rapidly increasing, they are relatively stable (it could be a small increase but not anything like the rapid rate of the mins increase.) So the daily range is much less (the difference between min and max.)  I don't disagree with what you wrote about 2050 either, it's just that we are not there yet.

 

Recent Julys have had mean minimum temperatures that are warmer than the mean 24-hour averages from past "cold" Julys. Probably after 2050, we will begin to see Julys where the mean minimum temperatures exceed the mean maximum temperatures from old-school cold Julys.

[wdrag]

Verification comments added to the initial post for July...  actually imo, decently outlooked. 

[TheClimateChanger]

On 7/30/2025 at 9:31 PM, TheClimateChanger said:

I project a mean July temperature of approximately 72.2F (+/- 0.5F) for the statewide average, which would make 2025 the 4th hottest July (and 4th hottest of any month) for the State of New York.

Pretty close! Officially checked in at 71.9F, matching 1901 & 1949 for 4th place overall.