The reason the sky is orange because of fires is due to the smoke particles.
The smoke particles that fly through the air and get into the atmosphere is what causes the sky to look orange from the fires.
Smoke particles from the wildfires "only allow yellow-orange-red light to reach the surface which in turn causes the sky to look and appear orange in color.
Once those smoke particles leave the earths atmosphere then the sky color will return to it's normal color which is usually blue.
But when a lot of smoke happens and goes up into the sky it can turn the sky to an orange color or different colors depending on the smoke particles.
The smoke particles can also make it very difficult to breathe as there could be harmful things in the smoke that is going up.
So if you're in an area with a lot of smoke and fires then make sure to wear a good face mask.