Phoenix Experiences Its Hottest Summer on Record for the Third Time in Five Years

[donsutherland1]

In what has become a seemingly regular occurrence beginning in 2020, Phoenix has experienced its hottest summer on record. Since 2020, Phoenix has eclipsed the summer mark in 2020, 2023, and again this year. A major theme, as was the case in 2020 and 2023 when the heat set in, was its persistence.

Summer 2024 got off to a blazing start with its hottest June, by far, on record. The sizzling June was followed by Phoenix’s second hottest July and second hottest month on record. July featured an 11-day extreme heat event (Clarke et al., 2014 methodology) during which the temperature reached or exceed 115° on six days. That was the second longest such event on record. Summer concluded with the third hottest August on record.

On account of the historic heat, Phoenix saw its longest stretches of 80° or above lows, 100° or above highs, and 105° or above highs:

• 80° or above lows: 74 days, June 5-August 17; old record: 51 days, July 1-August 20, 2023
• 100° or above highs: 97 days (as of August 31 and ongoing); old record: 76 days, June 10-August 24, 1993
• 105° or above highs: 63 days, June 5-August 6; old record: 56 days, June 24-August 18, 2023

Anthropogenic climate change amplified by the urban heat island effect is driving a warming of Arizona’s and Phoenix's summers. Data from a joint May 2024 report published by Climate Central, Red Cross Red Crescent Climate Centre and World Weather Attribution revealed that the influence of climate change has resulted in a 231.1% increase in Arizona’s days with temperatures above the 90^th percentile (1991-2020 baseline) over the figure expected without the influence of climate change.

The warming has accelerated in recent decades. Between 1950 and 2023, summers have warmed by 0.6° per decade in Phoenix. Since 1980, summers have warmed by 0.9° per decade. As a result, Phoenix has set summer records in 2020, 2023, and now 2024. As a result, the annual number of days on which the high temperature has exceeded the 90^th percentile for summer maximum readings (1991-2020 baseline) has increased from 6.5 days during 1961-1990 to 9.99 days during 1991-2020. The most recent 30-year moving average (1995-2024) is 12.7 such days per year (through August 31, 2024).

Select highlights:

 

Updates:

Phoenix records 100th 80° low temperature of the year

Progression of Phoenix's Record Streak of 100° Highs

Phoenix and Surrounding Area 100° Highs and 80° Lows

U.S. Sites with 110 or More Consecutive 100° Highs and Population

 

 

 

 

[donsutherland1]

Phoenix has now reached a record 100 consecutive 100-degree days.

[Typhoon Tip]

put a phys.org link over in Global Average Temperature 2024 

add s. korea to the list

[donsutherland1]

On September 5, Phoenix recorded a September record-tying 116° high temperature. A day later, Phoenix followed up with a new September monthly record high minimum temperature of 93°, which broke the old record by 2°. In California, Palm Springs recorded a low temperature of 95°, beating the September monthly mark by 3°. That was also tied for the second highest low temperature on record.

According to Climate Central's Climate Shift Index, this warmth was made at least 5 times more likely due to climate change.

[donsutherland1]

Yesterday, Phoenix recorded its 100th 80° low of the year, further extending its record. The combination of Urban Heat Island (UHI) Effect and ongoing anthropogenic warming has led to a dramatic explosion of the frequency of such hot nights.

[Typhoon Tip]

7 hours ago, donsutherland1 said:

Yesterday, Phoenix recorded its 100th 80° low of the year, further extending its record. The combination of Urban Heat Island (UHI) Effect and ongoing anthropogenic warming has led to a dramatic explosion of the frequency of such hot nights.

It’s mostly climate change…

I’ve never bought it that the urban he Island is a big enough factor in this thing because frankly, the urban heat is has been there since the middle of last century. So it’s on both sides of the trendline, and therefore should be equitable and eliminated as a common factor

[donsutherland1]

Phoenix reached 100° for the 113th consecutive day and 120th day overall this year. Six of the nine years with 120 such days have occurred since 2000 and all have occurred since 1988.

[GaWx]

23 hours ago, Typhoon Tip said:

It’s mostly climate change…

I’ve never bought it that the urban he Island is a big enough factor in this thing because frankly, the urban heat is has been there since the middle of last century. So it’s on both sides of the trendline, and therefore should be equitable and eliminated as a common factor

 The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%:
 

https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population

[bluewave]

16 hours ago, GaWx said:

 The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%:
 

https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population

While UHI is the reason for the urban areas like Phoenix running warmer than the rural locations especially at night, climate change is responsible for the whole region having their warmest summer on record including the low population Death Valley area.

 

 

[GaWx]

2 hours ago, bluewave said:

While UHI is the reason for the urban areas like Phoenix running warmer than the rural locations especially at night, climate change is responsible for the whole region having their warmest summer on record including the low population Death Valley area.

 

 

 Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV.

[Bhs1975]

 Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV.

Deserts soak up a lot of heat as it is so I'm not sure there would be much difference compared to the developed areas that has some grass and trees.


.

[donsutherland1]

Phoenix saw its record 113-day streak of 100° temperatures end today. Prior to this year, Phoenix has never had a stretch more than 76 days.

[bluewave]

17 hours ago, GaWx said:

 Indeed, I agree that CC/AGW is real and significant. My point to TT was that the UHI portion for large cities like Phoenix and LV shouldn’t be dismissed as insignificant. He said, “I’ve never bought it that the urban he Island is a big enough factor in this thing”. That’s what I was responding to. Perhaps I misinterpreted him. Maybe he just meant that UHI isn’t the dominant metric, which I’d lean toward though I could see it approach 50% in some of the faster growing large metros like LV.

Yeah, that’s what I meant by UHI is mostly evident at night. Notice how Phoenix didn’t really stand out with over 100 days this year as there were other Arizona stations with a similar number. But it was the leader in 80° minimums as the urban areas hold onto  the heat that builds up during the day. So while climate change lead to urban and rural stations both having their top ranking for warmest summer, Phoenix had many more 80° minimums due to UHI.

Phoenix had their warmest minimum average temperature of 87.5°. Casa Grande to the south with a population of only 56K had their warmest average minimum for the summer but it was cooler at 78.6. Care free also had their warmest average minimum temperature at 77.7 but with a population closer to onky 4K. So the differential is the UHI effect. The number 1 ranking is due to climate change. 
 

Climate perspectives site for comparison between rural, suburban, and urban sites with rankings, departures, and actual temperatures.

 

https://sercc.com/climate-perspectives/

 

Data below from XMACIS

Phoenix similar number of 100° days at 120.

Data for January 1, 2024 through September 18, 2024
Click column heading to sort ascending, click again to sort descending.

HAVASU ARIZONA	RAWS	125
TACNA 3 NE	COOP	124
ROBSON RANCH	COOP	121
PHOENIX AIRPORT	WBAN	120
Phoenix Area	ThreadEx	120
BUCKEYE 5N	COOP	119
BULLHEAD CITY	COOP	116
EAST MESA	COOP	116
LAKE HAVASU CITY	COOP	115
Lake Havasu City Area	ThreadEx	115

Phoenix lead in 80° minimums at 102.

Data for January 1, 2024 through September 18, 2024
Click column heading to sort ascending, click again to sort descending.

PHOENIX AIRPORT	WBAN	102
Phoenix Area	ThreadEx	102
MESA FALCON FIELD	WBAN	91
BULLHEAD CITY	COOP	86
SCOTTSDALE MUNICIPAL AP	WBAN	84
SMITH PEAK ARIZONA	RAWS	84
LAKE HAVASU CITY	COOP	83
Lake Havasu City Area	ThreadEx	83
YOUNGTOWN	COOP	78
YUMA PROVING GROUND	WBAN	77
YUMA MCAS	WBAN	75
Yuma Area	ThreadEx	75
BUCKEYE 5N	COOP	72
AJO	COOP	71
PHOENIX DEER VALLEY MUNICIPAL AP	WBAN	70

[Typhoon Tip]

On 9/16/2024 at 7:06 PM, GaWx said:

 The Phoenix area has grown nearly tenfold since 1960 and is now at 4.8 million. It has doubled in size just in the last 30 years. Minimizing the importance of UHI as a significant factor seems presumptuous to me. I’m not saying I think it is larger than CC (I fully believe in AGW), but rather I’m saying I think it is far from trivial and that it wouldn’t surprise me if it something like 30-40%:
 

https://www.macrotrends.net/global-metrics/cities/23099/phoenix/population

there's a lot of urban layouts across the continent that have not arrived through time with as much expansion, where also observing proportionate gains in t averages ( relative to their specific climate).  the idea should be consistent in the integral of the curve - which it is not.   in other words, the rises have been ubiquitous, while the rate of urban expansion was too variable to logically conclude hi effects 'as much'. 

i did not say phx's growth in that respect is no factor.  no issue with that.  what i said was, it's mostly climate change.  and it has to be anyway, because the climate provides the environment for the uhi feedback - not the other way around

i might be mistaken here but i suspect folks are thinking that the consiliency of cc  is actually not considering the urban heat island in the data ?   no

 

 

[donsutherland1]

2024 was the first year that saw large or major U.S. population centers affected by extreme duration heatwaves (100 or more consecutive days with 100° or above high temperatures). East Mesa and Phoenix, both of which are the only population centers with 250,000 or more people to experience such streaks went on to record 113 consecutive 100° or above highs. The list for 110+ such consecutive days is below.