Why is the sun red in Indiana? What’s causing unusual skies

Over the past few days, Central Indiana’s bright blue skies have at times been replaced with cloudless slates of gray.

And if Hoosiers do catch a glimpse of the sun, they’ve likely noticed it shining an unusual shade of red, creating colorful sunsets and lots of great Instagram opportunities. 

 Experts say the haze is the result of smoke from devastating West Coast wildfires spreading across the country at high altitudes.

Upper-level winds called jet streams move from west to east across the U.S. at 25,000 feet or so, said National Weather Service Meteorologist Mike Ryan. Those jet streams are picking up the smoke and carrying it all the way to Indiana, leading to the “milky” skies we’ve seen recently. 

“The very hazy sun like we had yesterday and we have today, that’s also because of all the particulates in the air because of the smoke,” Ryan told IndyStar Tuesday. “It’s making the sunrises and sunsets quite vivid and very colorful.”

A satellite image showing smoke from wildfires on the West Coast spreading across the country by the jet stream. Officials say the high level smoke is the cause of the hazy, cloudless skies and more colorful sunsets in Indiana.

Ryan said smoke will continue to have an impact on Indiana skies for the next couple of days until a cold front moves into the area Thursday.

He said that cold front will move a lot of the smoke situated in the upper level of the atmosphere to the south.

“It will kind of clear out the air mass. So as we go into the weekend, I think we’ll see a return to the very blue skies and brighter sunshine because the smoke will be shifted away,” Ryan said.

He added that despite wildfire smoke having an impact on how the sky looks, Hoosiers should not be concerned about it having a negative impact on overall air quality.

Unlike the West Coast where that smoke is closer to the surface, the smoke moving across the country is traveling at too high of an altitude to cause a significant dip in air quality.

In addition to pushing away the smoke, the weekend cold front will also deliver Indiana its first true fall preview. Ryan said the front will move through the area without delivering any rain, but expect to see a big difference in daily high temperatures.

“Friday and Saturday here across Central Indiana we’re expecting highs only around 70 and lows in the 40s, so it’s going to feel more fall-like,” he said. “We’ll see a little bit of a warm-up on Sunday back into the mid 70s, but still, it should be a really nice weekend for outdoor activities across the area.”

USA Today contributed to this story.

Call IndyStar reporter Justin L. Mack at 317-444-6138. Follow him on Twitter: @justinlmack.