Hazy Days in Summer—What’s the Cause?

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Hazy Days in Summer—What’s the Cause?

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You may hear meteorologists refer to “visibility” during the weather forecast. At a basic level, this describes how far away you can be from something outside and still see it. This is often measured from airports and weather stations, and can impact travel safety and the ability to predict weather patterns. In the summertime, it’s not uncommon to have reduced visibility during certain times of the day due to haziness nearby or that you can see in the distance.

So, what’s causing those hazy skies in the summer?

Factors Impacting Visibility



Summertime sees an increase in travel both by airplane and automobile. These modes of transportation produce large amounts of airborne pollution, which you can especially notice around large population centers. This particulate matter combines with other sources of air pollution to scatter the sun’s light and create haziness and lower visibility. Outdoor air quality can also impact the quality of the air inside your home, making proper air quality management essential.


On hot, humid days in summer, particulate matter is more likely to stay in the air longer and cause reduced visibility. Paired with winds that stir up pollution, the increased moisture in the air may hold particulate matter aloft for several days at a time and cause a hazy appearance in the sky. Generally, haziness decreases on days with more moderate temperatures, humidity, and wind.

Wildfire Smoke

Wildfire season is here, adding large amounts of smoke to the air both in areas directly in the path of wildfires and in places hundreds of miles away where wind can carry the smoke. This can significantly reduce visibility, and cause the sky to take on strange colors or have a general, gray haze. When the air is saturated enough, you may even smell smoke when you walk outside.

Lack of Precipitation

Most areas of the United States see less precipitation during the summer. Rainfall typically clears particulate matter from the air, which can increase visibility. With long stretches of hot, humid days and more direct sunlight during the summer, the sky can hold onto particulate matter and remain hazy.

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