What Makes the Sky Turn Orange? Potential Causes

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Outdoor education expert Hannah Young explains the science behind an orange sky

Co-authored by Hannah Young and Eric McClure

Last Updated: August 10, 2026 Fact Checked

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Possible Causes

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Safety Tips

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Orange Sky Science

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Video

Everyone loves a colorful orange sunset, but if the sky looks orange in the middle of the day, it can be a little eerie. So what’s causing the unusual color and should you be worried about the air quality? We talked to an outdoor education expert to learn more about the scientific phenomenon behind an orange sky and what causes it. We’ll also touch on some safety tips!

Why Is It Orange Outside Right Now?

An orange sky can be caused by wildfires, storms, or bad air quality. If the sky is orange, follow these safety tips:

Stay inside if possible and keep your doors and windows closed.
If you have to go outside, wear an N95 mask.
Look online or follow local news to monitor the air quality index (AQI).

Section 1 of 3:

Possible Causes of an Orange Sky

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1
Wildfire smoke The particles in wildfire smoke are primarily made up of tiny bits of soot, ash, and carbon. In the right combination and size, those particles can trigger the scattering needed to produce an orange sky.^{[1]
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- If the smoke is brown or white, it’s caused by Mie scattering. Rayleigh scattering isn’t the only type of scattering. Mie scattering occurs when the particles in the air are the same size as the wavelength of light (as opposed to the wavelength of radiation, with Rayleigh scattering). Mie scattering removes all color, leaving the air white or brown.
Meet the wikiHow Expert

Hannah Young is an outdoor education expert who specialties in educating others on backpacking, hiking, land ethics, and wilderness restoration.
The most polluted cities in the world are often photographed with orange skies because the air is thick with aerosol particles. These particles are notorious for causing Rayleigh scattering.^{[2]
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Volcanic ash The gases created during a volcanic eruption are often the perfect size to trigger Rayleigh scattering. This is why volcanoes tend to be so photogenic—the sky around active volcanoes is often full of these particles and they change the color of the sky.
- Volcanic ash can travel incredibly far. A volcano eruption in Russia can easily impact the quality of the air in the United States, for example.^{[3]
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  Research source} The same way wildfire smoke particles travel, volcano particles travel as well.
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Impending thunderstorm Storm clouds normally contain a lot of ice, moisture, and particles from evaporated water that can cause light scattering. This typically produces a green or purple sky, but it can also trigger an orange sky depending on the particles themselves.^{[4]
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- You normally can’t see the orange sky by the time the thunderstorm is over you because the sun gets blocked by the thick clouds.
Dust storm particles often cause the same kind of light scattering as manmade forms of pollution do. In the event of a sand storm specifically, it’s probably the only case where an orange sky is caused by something actually orange.^{[5]
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Section 2 of 3:

Poor Air Quality Safety Tips

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Wear a tight-fitting N95 mask if it’s orange outside. If you don’t have an N95, a NIOSH-approved mask or P100 mask will also work. If you spot an orange sky outside and it’s not sundown or sunset, there’s something going on in the air that is potentially bad for your health. If you have to go outside (it’s best that you don’t, but that’s not always an option), wear a mask.^{[6]
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United States Environmental Protection Agency
Independent U.S. government agency responsible for promoting safe environmental practices

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All of that junk floating around in the air is not good for your health, so while you’re at home, don’t let any outside air in. Keep the fans running and run the fan on your HVAC system if you have central air. The circulating air will help keep the air from getting stale while you wait out the orange sky.
Use the federal air monitoring service to find the air quality where you live at a given time. Here are the guidelines on what the scores mean:^{[7]
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Understanding AQI Levels
AQI	Meaning	What You Should Do
0-50	The air quality is safe.	Nothing. Enjoy the outdoors!
51-100	The air quality is acceptable.	Avoid strenuous outdoor activities if you have health risks.
101-150	The air quality is poor. Sensitive groups may encounter adverse effects, but healthy people should be okay.	Avoid going outdoors if you have underlying health issues. If you don't have health issues, avoid strenuous outdoor activities.
151-200	The air quality is bad. Everyone may encounter health effects, with sensitive groups being susceptible to serious risk.	Everyone should avoid going outside. If you have to, wear a mask.
201-300	The air quality is very bad. Health impacts are high risk for everyone.	Avoid going outside unless absolutely necessary.
301+	The air quality is terrible. Everyone is highly likely to suffer negative health effects.	Do not go outdoors unless it is a matter of life and death.

Section 3 of 3:

What's the science behind orange skies?

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An orange sky is caused by light scattering when it hits tiny particles. “Visible light, including what is emitted from the sun, exists in a wide range of wavelengths,” explains Young. “In the absence of smoke or pollution, the molecules in our atmosphere tend to scatter short wavelengths of light from the sun, which our eyes interpret as the color blue. With smoke or other types of pollution, new molecules are introduced into the atmosphere. These molecules tend to be larger in size, allowing them to scatter light with longer wavelengths. Our eyes interpret these longer wavelengths as warm colors like orange and red.^{[8]
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Expert Source

Hannah Young
Outdoor Education Expert

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- Sunlight isn’t actually white (or yellow). It is made of every color in the rainbow, which is why you can filter certain colors out. This is how 3D glasses and blue light glasses work! They filter out certain wavelengths of light.
- This is why sunsets are orange and red. Young explains, “As the sun gets lower on our horizon, it has to travel through more of our atmosphere before reaching our eyes. The longer travel means that more of the short wavelengths (blues) are scattered before the light reaches us, leaving only long wavelengths for us to perceive.”^{[9]
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  Hannah Young
  Outdoor Education Expert
  
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- If the sky is orange and it’s not sunset (or sunrise), something is in the air. Rayleigh scattering should not occur if there’s nothing in the air, so if it’s the middle of the day and you’re seeing orange skies, something abnormal is up, like smoke or air pollution.