Phoenix Shatters Records: Warmest February/Winter and Mind-Boggling March

[GaWx]

1 hour ago, frontranger8 said:

Are we gonna talk about how Fairbanks had their coldest DJFM on record, and shattered their coldest March on record by over 3 degrees?

The contrast sure is fascinating! Anchorage also is getting their coldest March on record. Because this thread is centered on Phoenix, I talked about the record cold Fairbanks in another thread, including in this post:

 

[GaWx]

 From outspoken pro met. Chris Martz fwiw:

 Any comments?

[LongBeachSurfFreak]

Not a very good example. FOK was more of a microclimate, if it's even a legit measurement. It was lower than any other location, regardless of rural/urban location, for hundreds of miles. Nothing lower until deep into New England. It was like 5F colder than even the coldest personal weather stations on Long Island.

It’s a legit ob from an ASOS station.
As far as a micro climate sure. It’s in the heart of the dwarf pine barrens which is characterized by extremely sandy soils and radiates better then any non deep valley location on the east coast.
Regardless of KFOK, KJK was almost 10 degrees cooler then the park or KLGA.


.

[donsutherland1]

11 hours ago, GaWx said:

 From outspoken pro met. Chris Martz fwiw:

 Any comments?

Bad methodology. Notice he uses MT and WY. 90s in March are virtually assured to be near or at zero. Thus he assures himself the kind of conclusion he seeks. A more robust approach would involve standardized measurements, e.g., the number of highs 1 sigma, 2 sigma, etc., above the 20th century baseline. 

[chubbs]

52 minutes ago, donsutherland1 said:

Bad methodology. Notice he uses MT and WY. 90s in March are virtually assured to be near or at zero. Thus he assures himself the kind of conclusion he seeks. A more robust approach would involve standardized measurements, e.g., the number of highs 1 sigma, 2 sigma, etc., above the 20th century baseline. 

Another issue: the shelters 100 years ago were not aspirated. Inadequate or poorly sited shelter ran warm. With his number of days metric easy for one or two sites with bad data to bias the result. We saw that in the Chester county, where spuriously warm data from Phoenixville in the 1930s and 1940s biased the >95F day data, by providing the overwhelming majority of the County 95F+ days in that period. 

Better to show the data for every station like chart below. That way a few bad apples don't skew the data. Threadx cities plotted below have the longest climate records.

[GaWx]

1 hour ago, donsutherland1 said:

Bad methodology. Notice he uses MT and WY. 90s in March are virtually assured to be near or at zero. Thus he assures himself the kind of conclusion he seeks. A more robust approach would involve standardized measurements, e.g., the number of highs 1 sigma, 2 sigma, etc., above the 20th century baseline. 

Thanks, Don. He also said “I may look at March days with maximum temperatures at or above the 90th percentile for better measure.”

 If he actually does this and posts it, would that be a better approach? 

[TheClimateChanger]

1 hour ago, chubbs said:

Another issue: the shelters 100 years ago were not aspirated. Inadequate or poorly sited shelter ran warm. With his number of days metric easy for one or two sites with bad data to bias the result. We saw that in the Chester county, where spuriously warm data from Phoenixville in the 1930s and 1940s biased the >95F day data, by providing the overwhelming majority of the County 95F+ days in that period. 

Better to show the data for every station like chart below. That way a few bad apples don't skew the data. Threadx cities plotted below have the longest climate records.

Also, the afternoon/early evening observation time common at the cooperative sites in the earlier decades often tacks on an additional day at or above a threshold temperature to warm spells, since the set temperature for the following day would be only a little bit colder than the daily high.

[donsutherland1]

2 hours ago, GaWx said:

Thanks, Don. He also said “I may look at March days with maximum temperatures at or above the 90th percentile for better measure.”

 If he actually does this and posts it, would that be a better approach? 

Yes. That would be better. The instrument details mentioned by @chubbs could still play a role at some sites.

[donsutherland1]

Powered by a monster heat dome that would be a rarity during the summer, Phoenix and the Southwest experienced mind-boggling warmth during March. 

Chart 1: Daily Temperatures:

 

Chart 2: Return Time of Monthly Mean Temperature (Historic Period):

The warmth has been persistent since December. December, February, and March set new records for warmest December, February, and March on record. As a result, Phoenix also experienced its warmest December-March period by a large margin.

 

[donsutherland1]

Phoenix was so warm during March 2026 that its mean monthly low, mean monthly high, and mean monthly temperatures would all have ranked second hottest on record for April. Numerous March temperature records surpassed the most extreme values experienced during April.

 

 

[Stormchaserchuck1]

Good stuff Don. +4.2F over DJFM number 2 is amazing stuff. 

[Stormchaserchuck1]

I plotted from Don's warmest DJFM Phoenix years.. it's surprising that the DJFM that occurred a year later is cold in the SW. It has historically snapped back the following year. 

[WolfStock1]

On 3/31/2026 at 7:58 PM, GaWx said:

 From outspoken pro met. Chris Martz fwiw:

 Any comments?

 

That's broad temperatures over a long timeframe and a large area - i.e. climate.   This thread is about the recent weather in one city, not general climate.

[Typhoon Tip]

Yo Don... something to maybe keep an eye on.

The longer range ensembles from all, EPS/GEPS/GEFS are doing something interesting. 

First, a strong -PNA wave function sweeps the continent. An ~ 90W ridge balloons.  However, just when the heat is poised to move in here, we either only get day or so, or perhaps a failure/ shunt entirely. The reason is the total scaffolding suddenly, rather abruptly ( suspicious, more below) en mass the fields roll back out W. 

Not clear why that is happening and it is suss, but that reposition to the Sonoran Desert/PHX region instead  would make Europe seem a like a mild day to the Inuit.   Talking 120+ to perhaps the big 1  3 0s

Hell hath no fury should a Sonoran Heat Release ever actually happen. 

About that... not sure it will.  The hemisphere has been persistent really since last summer.  Year's worth or more ( frankly) and counting.  Hell bent on making sure we continue what happened all last winter:   SE Can/NE U.S. is the coolest relative to the whole planet despite every month at a Global empirical result being 1, 2 or 3 warmest since thermometers were invented.   Right now, currently being in 3rd place for historic inferno at a Global scale for June; which is likely end in 2nd or even vying for 1st. This looking back along this behavior, it's about a .75 to .12 C gain to loss ratio/behavior,

so granted, I'm only roughing a linear extrapolation; if so the abv slope figures for about 16.8 by the end these next 9 days but we'll see....

One thing I'm noticing about that retro/heat rollback west, however... It looks too sudden, at too large of a scale.  The entire mass of the planet won't do this typically.  It seems to be happening right as the entire scope of the hemisphere ( in all three ens systems) suddenly abandons the anomaly distribution. All wave functions, on-going, just abruptly dissolve/collapse into base-line above average everywhere ... Odd. that en mass unilateral holistic behavior all at once ... mmm that's suss to me.   But we'll see. 

 

[donsutherland1]

3 hours ago, Typhoon Tip said:

Yo Don... something to maybe keep an eye on.

The longer range ensembles from all, EPS/GEPS/GEFS are doing something interesting. 

First, a strong -PNA wave function sweeps the continent. An ~ 90W ridge balloons.  However, just when the heat is poised to move in here, we either only get day or so, or perhaps a failure/ shunt entirely. The reason is the total scaffolding suddenly, rather abruptly ( suspicious, more below) en mass the fields roll back out W. 

Not clear why that is happening and it is suss, but that reposition to the Sonoran Desert/PHX region instead  would make Europe seem a like a mild day to the Inuit.   Talking 120+ to perhaps the big 1  3 0s

Hell hath no fury should a Sonoran Heat Release ever actually happen. 

About that... not sure it will.  The hemisphere has been persistent really since last summer.  Year's worth or more ( frankly) and counting.  Hell bent on making sure we continue what happened all last winter:   SE Can/NE U.S. is the coolest relative to the whole planet despite every month at a Global empirical result being 1, 2 or 3 warmest since thermometers were invented.   Right now, currently being in 3rd place for historic inferno at a Global scale for June; which is likely end in 2nd or even vying for 1st. This looking back along this behavior, it's about a .75 to .12 C gain to loss ratio/behavior,

so granted, I'm only roughing a linear extrapolation; if so the abv slope figures for about 16.8 by the end these next 9 days but we'll see....

One thing I'm noticing about that retro/heat rollback west, however... It looks too sudden, at too large of a scale.  The entire mass of the planet won't do this typically.  It seems to be happening right as the entire scope of the hemisphere ( in all three ens systems) suddenly abandons the anomaly distribution. All wave functions, on-going, just abruptly dissolve/collapse into base-line above average everywhere ... Odd. that en mass unilateral holistic behavior all at once ... mmm that's suss to me.   But we'll see. 

 

It will be interesting to see how this ultimately plays out. I suspect that the Sonoran Desert has yet to see its highest temperatures this summer, even if the forecast values for this week verify.