I had this random question pop into my head, could black LED streetlights burn out quicker due to it attracting heat? I can see how this could happen.

Black works in both directions regarding radiation. When light / IR is hitting it, it heats up. But the opposite also works: when the surrounding is darker and colder, it will radiate heat much more easily than white or blank metal, towards colder areas (especially upwards towards space, try pointing an IR thermometer into a clear night sky. The reading can be sub-arctic temperatures!)

So blacks will help to cool things when it is dark. However, during daytime and evening hours, it could also make it very hot. I don't know, which of the two effects will be the stronger one regarding the overall net effect on lifetime however.

Black works in both directions regarding radiation. When light / IR is hitting it, it heats up. But the opposite also works: when the surrounding is darker and colder, it will radiate heat much more easily than white or blank metal, towards colder areas (especially upwards towards space, try pointing an IR thermometer into a clear night sky. The reading can be sub-arctic temperatures!)

So blacks will help to cool things when it is dark. However, during daytime and evening hours, it could also make it very hot. I don't know, which of the two effects will be the stronger one regarding the overall net effect on lifetime however.

So the lights wouldn’t overheat while in nighttime operation? It must get really hot if it’s really hot out, especially if it’s dayburning!

So the lights wouldn’t overheat while in nighttime operation? It must get really hot if it’s really hot out, especially if it’s dayburning!

During the night (after cooling down from daytime heat), it would actually run cooler than an identical white or blank lantern. Black (and matte) surfaces are more effective radiators of heat: this is the reason why heatsinks for electronics that rely on radiative cooling are often black.

But that indeed comes with the massive punishment daytime when the sun is shining..

During the night (after cooling down from daytime heat), it would actually run cooler than an identical white or blank lantern. Black (and matte) surfaces are more effective radiators of heat: this is the reason why heatsinks for electronics that rely on radiative cooling are often black.

But that indeed comes with the massive punishment daytime when the sun is shining..

That’s cool! At least they’re not on during the daytime (if they’re not dayburning) as that would be a problem. Generally here in New England, it stays pretty cool with a few 90 degree summer days but it’s nothing like Florida or California.

During the night (after cooling down from daytime heat), it would actually run cooler than an identical white or blank lantern. Black (and matte) surfaces are more effective radiators of heat: this is the reason why heatsinks for electronics that rely on radiative cooling are often black.

Well, to really help with cooling, it should be "black" for the wavelengths corresponding to the operating temperatures, so we are talking about few um wavelength IR. And there virtually any common organic material (so all the paints) is near black, even when in visible it looks like snow white.
For not receiving heat from the sun, the "blackness" in the sun most energetic wavelength range (on the Earth surface, so 1..0.4um) is what dictates how much heat it gets.
So indeed, what is visibly black, will become way hotter during the day, but not much difference when operating at night.

I've used a half dozen different thermal cameras, and I can tell you for sure that at IR, any painted surface is "black". It would absorb more sun energy during the day, but the paint pigment would have virtually no effect on cooling at night.

Well, to really help with cooling, it should be "black" for the wavelengths corresponding to the operating temperatures, so we are talking about few um wavelength IR. And there virtually any common organic material (so all the paints) is near black, even when in visible it looks like snow white.
For not receiving heat from the sun, the "blackness" in the sun most energetic wavelength range (on the Earth surface, so 1..0.4um) is what dictates how much heat it gets.
So indeed, what is visibly black, will become way hotter during the day, but not much difference when operating at night.

Ambient wind that is nearly always present up around these fixtures will also add to the fixtures cooling.

Thank you guys for helping me out on this!

I've used a half dozen different thermal cameras, and I can tell you for sure that at IR, any painted surface is "black". (...)

Oh, I was not aware of this. I do have some experience looking through thermal cameras, but I only ever compared blank, polished metal surfaces to the same surface but painted (visible) black for proper thermal readings. Then the overall thermal balance for black streetlights must indeed be worse than for white (or other color) streetlights, as long as they are painted.

Thermal dissipaton by radiation is directly proportional to the fourth power of the temperature of an object - so at low temperatures, i.e. the temperature of any electronic devices, radiative heat loss is virtually insignificant.  A matt black surface will radiate slightly more heat but the quantity is so tiny that it's far more important to invest in heatsinks made from alloys having high conduction losses, and to design the finned surface for maximum convective losses.  Conclusion is that I can see only drawbacks to making an outdoor LED luminire in black finish.