(WSIL) -- A less than blue sky can be attributed to wild fire smoke.
There are 78 large fires across the United States, which are currently blazing through more than a million acres. Those and other large fires in Canada are now contributing to smoky skies over much of the U.S.
SIU Professor, Justin Schoof says this is fairly common.
"Every summer this happens, it's just that you don't always get very much smoke down toward the surface. But most summers you have some wildfire activity out west. The fires in this case that are causing the problem, most of them are actually pretty far north into Canada, and that's why they're coming down on that ridge because the ridge is really to our north."
While the smoke will be noticeable, much of it will remain too high above our heads for it to affect us. Schoof says in that case, folks here shouldn't need to worry about air quality issues. Even though most of the smoke will likely not have a large impact here, if you are vulnerable to poor air quality, it may be best to limit your time outdoors.