We moved to Tempe back around June 1987 and I had the summer off while the better half went to work. We moved from Gainesville, FL. One of us was raised in S. FL and the GA. In Gainesville, we lived through the summers with an apartment and cars w/o AC. I worked in exterior renovation during one summer in Atlanta when it reached 100F regularly, and the summer after high school in S. FL installing attic HVAC metal ducts in new construction. So we thought we knew heat.
So I'm in the apartment in June and the complex has got a pool so like I'd always done I put the swimsuit on, grabbed a towel, and strode barefoot across the parking lot in the direction of the pool. It was probably 101F, nice day for June. About halfway across the lot I realized I was burning my (tough) feet. I'm a practical person and noticed the white stripes in the lot and ran to one. YUP! At least 20F cooler. Ever since I've wondered why you couldn't do something like that white paint for all the asphalt and concrete. Turns out you can. Hooray! I'm in Tucson now (it's currently 106F/22%). I'm out at 5AM for a bike ride many days and the lows have been steadily climbing over the past decades. Was 84F this morning, the lows increasing every day this week, YUK. When I ride out to the actual desert it gets noticeably cooler, maybe 5F. I want them to take this stuff and just coat entire Tucson metro area with it.
> Same street, two surfaces: Phoenix tested a reflective coating against regular asphalt (representative image). Image Credits: ChatGPT
Sigh. Fake pictures, plus internal links to the India Times.
The city of Phoenix has some web pages on this. There are pictures of the real coating, pictures of it being sprayed on, and links to technical studies. Phoenix has been doing this since 2021, gradually spraying more streets. It looks like grey paint but has asphalt in it.
Phoenix actually has plenty of water because of the Salt River. Tucson gets CAP water which just got whacked pretty hard in the Colorado River negotiations (20% CAP cut I think?) and I was surprised to learn that the City of Tucson has managed its water efficiency so well that nothing has to change much, price for instance.
If water supply does eventually require changes, the technically obvious and very easy change would be to reduce agriculture (pecans, alfalfa, cotton) by whatever amount is needed. Politically though, that's going to be fun. That agriculture is backed by Big Money.
The heat sucks, but the sun is very bright and my comfortable 75F house generally has a zero or small electrical bill because my roof is covered in solar panels.
The heat sucks hard for 3 months. The rest of the year is fucking glorious.
Just to be a pedant, and because this fact tends to surprise people, asphalt is concrete.
Concrete is a generally defined as any mineral aggregate (so rocks and stones) mixed with a binder (normally cement, but bitumen in the case of asphalt).
As for why roads are normally made out of “normal” concrete, it’s very expensive to build roads like that. Pavements are cheaper to build out of concrete because they only carry the weight of pedestrians, not lots of rolling vehicles. You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension. Asphalt concrete cheats by being flexible, so minor imperfections in the surface or sub-base don’t become sources of critical failures (although they can become pot holes). Asphalt is also cheaper and easier to patch repair, but doesn’t last as long as proper cement road surfaces.
To be even more of a pedant, because asphalt is a subset concrete, any comparison between asphalt and concrete is automatically implied as a comparison between asphalt and non-asphalt concrete, and to specify would be redundant.
It's just like when saying "man vs animal", everyone knows that man is a type of animal, but it's implied that it's "man vs non-man animal".
Possibly. But I noticed offhand in the DFW, Texas area there many local streets - sometimes flat ground-level parking lots - paved entirely in concrete, not just highways. Apparently for them the up front investment in "normal" (portland?) concrete is more economical.
The cost would be a lot lower given sufficient advance planning to stop digging it up and patching it so often. Different parts of local government often don't coordinate enough with each other, so a brand new road gets put in, and then dug up and patched 1-2 months later. Asphalt is easier and thus cheaper to patch, and the result looks...well, as bad as asphalt always does, rather than the obvious patch spots/lines on concrete.
Ideally, put in concrete roads that include conduits.
There's a lot of protectionism around asphalt maintenance.
I knew a city manager that got a city out of a major projected shortfall, without cutting any services, by investing in redicing long-term expenses.
He was celebrated for it, then fired, because the asphalt company that lost its contract had more political sway than the parks and recreation or public education departments that he fought for.
I was in Tempe/Phoenix region during the peak of summer (August I remember). It was 115°F+ everyday. Even after dinner, when I wanted to stroll around outside the mall near ASU, it was 90°F. It was insane how hot it was. I’ve lived in Houston and the heat was not even that high. But Phoenix has almost zero humidity in the summer which makes the heat a lot more bearable comparing to the sauna in Houston. Anyway, would not go there during summer again!
The amount of concrete and lack of green cover is a major problem.
We’re currently away from home in a city that has waaaay more concrete than where we live and the temperature increase is horrible, even when the reported temperature is the same.
The US has built horrible cities for a couple of generations now. The incoming increase it temps will hopefully force them to redesign ie the tree plan for NYC
Phoenix is the hottest city I've ever visited. The people were great, but I struggle to imagine why anyone would want to live there, let alone build semiconductor factories in an area already short on water supply.
This is something that I fail to understand - why are there so many people there? Is there unobtainium in the hills that can only be mined from the region? Prior to modern air conditioning, why would people setup there when there are seemingly more hospitable areas?
People did prefer living in colder areas before AC.
The arrival of AC meant there was suddenly a lot of very cheap land around cities that are extremely unpleasant without AC. This resulted in migration and a housing boom which drives up the economy attracting more people.
Sure enough, Wikipedia says the population in 1940 was only 65k (which is still too many, but whatever). I would still assume that AC installation was very uneven and a luxury at the time.
Suburbia requires land and desert land is very cheap when market-priced, so long as the true costs of drinking and lawn grass watering for the land are externalized. Unfortunately, that leaves the region exposed to the Colorado watershed collapse and associated “which metropolis gets the axe” politics:
Having walked on it, it really doesn't feel any hotter than the sidewalks. And in the morning and evening (only time it really makes sense to go walking there most of the year) it's significantly nicer than the asphalt.
The only person I know that lived near there had fibromyalgia, and had deliberately moved there from NY as they felt better in that climate. So YMMV I guess. They didn't actually live in phoenix, don't know how much difference that made.
Can confirm the heat. In the early 1990s I got bumped from a flight out of Phoenix because it was so hot the density altitude meant they couldn't load the plane as heavily as usual.
We moved to Tempe back around June 1987 and I had the summer off while the better half went to work. We moved from Gainesville, FL. One of us was raised in S. FL and the GA. In Gainesville, we lived through the summers with an apartment and cars w/o AC. I worked in exterior renovation during one summer in Atlanta when it reached 100F regularly, and the summer after high school in S. FL installing attic HVAC metal ducts in new construction. So we thought we knew heat.
So I'm in the apartment in June and the complex has got a pool so like I'd always done I put the swimsuit on, grabbed a towel, and strode barefoot across the parking lot in the direction of the pool. It was probably 101F, nice day for June. About halfway across the lot I realized I was burning my (tough) feet. I'm a practical person and noticed the white stripes in the lot and ran to one. YUP! At least 20F cooler. Ever since I've wondered why you couldn't do something like that white paint for all the asphalt and concrete. Turns out you can. Hooray! I'm in Tucson now (it's currently 106F/22%). I'm out at 5AM for a bike ride many days and the lows have been steadily climbing over the past decades. Was 84F this morning, the lows increasing every day this week, YUK. When I ride out to the actual desert it gets noticeably cooler, maybe 5F. I want them to take this stuff and just coat entire Tucson metro area with it.
> Same street, two surfaces: Phoenix tested a reflective coating against regular asphalt (representative image). Image Credits: ChatGPT
Sigh. Fake pictures, plus internal links to the India Times.
The city of Phoenix has some web pages on this. There are pictures of the real coating, pictures of it being sprayed on, and links to technical studies. Phoenix has been doing this since 2021, gradually spraying more streets. It looks like grey paint but has asphalt in it.
Good idea, AI slop article.
[1] https://www.phoenix.gov/administration/departments/streets/i...
I just simply don't understand why so many people live in Pheonix given the issues with heat and lack of water sources.
Phoenix actually has plenty of water because of the Salt River. Tucson gets CAP water which just got whacked pretty hard in the Colorado River negotiations (20% CAP cut I think?) and I was surprised to learn that the City of Tucson has managed its water efficiency so well that nothing has to change much, price for instance.
If water supply does eventually require changes, the technically obvious and very easy change would be to reduce agriculture (pecans, alfalfa, cotton) by whatever amount is needed. Politically though, that's going to be fun. That agriculture is backed by Big Money.
The heat sucks, but the sun is very bright and my comfortable 75F house generally has a zero or small electrical bill because my roof is covered in solar panels.
The heat sucks hard for 3 months. The rest of the year is fucking glorious.
The equivalent of 6.6°C according to google.
Why not use concrete instead of asphalt? This person registered a 20 degree difference between the concrete sidewalk and asphalt road.
https://www.reddit.com/r/phoenix/comments/14o5bdu/a_comparis...
Just to be a pedant, and because this fact tends to surprise people, asphalt is concrete.
Concrete is a generally defined as any mineral aggregate (so rocks and stones) mixed with a binder (normally cement, but bitumen in the case of asphalt).
As for why roads are normally made out of “normal” concrete, it’s very expensive to build roads like that. Pavements are cheaper to build out of concrete because they only carry the weight of pedestrians, not lots of rolling vehicles. You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension. Asphalt concrete cheats by being flexible, so minor imperfections in the surface or sub-base don’t become sources of critical failures (although they can become pot holes). Asphalt is also cheaper and easier to patch repair, but doesn’t last as long as proper cement road surfaces.
https://en.wikipedia.org/wiki/Asphalt_concrete
To be even more of a pedant, because asphalt is a subset concrete, any comparison between asphalt and concrete is automatically implied as a comparison between asphalt and non-asphalt concrete, and to specify would be redundant.
It's just like when saying "man vs animal", everyone knows that man is a type of animal, but it's implied that it's "man vs non-man animal".
Possibly. But I noticed offhand in the DFW, Texas area there many local streets - sometimes flat ground-level parking lots - paved entirely in concrete, not just highways. Apparently for them the up front investment in "normal" (portland?) concrete is more economical.
> You need a pretty thick slab with rebar in it if you want to build a road surface from it, due to how weak cement concrete is under tension.
A lot of states use JPCP now for highways that doesn’t require rebar.
Huge temperature swings is a big part. Most people don't realize how cold it can get in the desert at night.
Cost.
The cost would be a lot lower given sufficient advance planning to stop digging it up and patching it so often. Different parts of local government often don't coordinate enough with each other, so a brand new road gets put in, and then dug up and patched 1-2 months later. Asphalt is easier and thus cheaper to patch, and the result looks...well, as bad as asphalt always does, rather than the obvious patch spots/lines on concrete.
Ideally, put in concrete roads that include conduits.
There's a lot of protectionism around asphalt maintenance.
I knew a city manager that got a city out of a major projected shortfall, without cutting any services, by investing in redicing long-term expenses.
He was celebrated for it, then fired, because the asphalt company that lost its contract had more political sway than the parks and recreation or public education departments that he fought for.
I was in Tempe/Phoenix region during the peak of summer (August I remember). It was 115°F+ everyday. Even after dinner, when I wanted to stroll around outside the mall near ASU, it was 90°F. It was insane how hot it was. I’ve lived in Houston and the heat was not even that high. But Phoenix has almost zero humidity in the summer which makes the heat a lot more bearable comparing to the sauna in Houston. Anyway, would not go there during summer again!
The amount of concrete and lack of green cover is a major problem.
We’re currently away from home in a city that has waaaay more concrete than where we live and the temperature increase is horrible, even when the reported temperature is the same.
The US has built horrible cities for a couple of generations now. The incoming increase it temps will hopefully force them to redesign ie the tree plan for NYC
Is the lack of green cover really problem? Seems like the lack of green cover would be natural for that area.
Are most cities naturally occuring?
Yeah, NYC's tree plan would be quite the disaster in Phoenix, I would think.
Non-trash local source with actual photographs instead of AI-generated imagery
https://www.12news.com/article/news/local/arizona/phoenix-to...
This forwards me to a Youtube channel page.
Works fine for me. Maybe you're geoblocked?
edit: screengrab that shows the color difference: https://wormhole.app/a7Alp9#AQrGDBYIigvXaN7Wx1uJJA
Plants would lower it even more
>but pedestrians faced higher radiant heat
As would vehicles.
Phoenix is the hottest city I've ever visited. The people were great, but I struggle to imagine why anyone would want to live there, let alone build semiconductor factories in an area already short on water supply.
This is something that I fail to understand - why are there so many people there? Is there unobtainium in the hills that can only be mined from the region? Prior to modern air conditioning, why would people setup there when there are seemingly more hospitable areas?
People did prefer living in colder areas before AC.
The arrival of AC meant there was suddenly a lot of very cheap land around cities that are extremely unpleasant without AC. This resulted in migration and a housing boom which drives up the economy attracting more people.
Sure enough, Wikipedia says the population in 1940 was only 65k (which is still too many, but whatever). I would still assume that AC installation was very uneven and a luxury at the time.
I would guess that swamp coolers were fairly common.
Suburbia requires land and desert land is very cheap when market-priced, so long as the true costs of drinking and lawn grass watering for the land are externalized. Unfortunately, that leaves the region exposed to the Colorado watershed collapse and associated “which metropolis gets the axe” politics:
America’s desert metropolis Is on the short list to lose water (6 hours ago) https://www.nytimes.com/2026/08/23/us/arizona-canals-colorad...
(I suspect the interstate highway system also contributed to migrations, but haven’t done the research.)
Large silver and turquoise mines, basically.
Cheap land
Having walked on it, it really doesn't feel any hotter than the sidewalks. And in the morning and evening (only time it really makes sense to go walking there most of the year) it's significantly nicer than the asphalt.
The only person I know that lived near there had fibromyalgia, and had deliberately moved there from NY as they felt better in that climate. So YMMV I guess. They didn't actually live in phoenix, don't know how much difference that made.
Can confirm the heat. In the early 1990s I got bumped from a flight out of Phoenix because it was so hot the density altitude meant they couldn't load the plane as heavily as usual.
Does anyone have any real photos of the reflective asphalt?