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Why does a sunny sky mean my eyes and throat are so scratchy in Houston?

Ample sunshine feels great but also carries a threat for poor air quality for the rest of this week

AQI Index for Wednesday (Copyright 2025 by KPRC Click2Houston - All rights reserved.)

We’re all enjoying the sunshine and break from the rain this week in Houston.

However, sunny skies and a strong dome of high pressure also means our air quality can actually suffer under these warm afternoons.

Air quality alert for Wednesday (Copyright 2025 by KPRC Click2Houston - All rights reserved.)

How is that possible?

Sunshine creates ozone, which is a normal by-product of the radiational energy that the sun emits as it reaches the earth’s surface.

We also have a large dome of high pressure sitting above Texas which serves as a sealant for the ozone, keeping it trapped close to the surface vs allowing it to escape back to space.

Heat pressure dome (Copyright 2025 by KPRC Click2Houston - All rights reserved.)

Think of it like an upside down bowl; anything that is underneath the bowl is trapped and can’t get out. The atmosphere works the same way as high pressure compresses the air and traps pollutants, pollen and gasses like ozone closer to the surface.

AQI Index for Wednesday (Copyright 2025 by KPRC Click2Houston - All rights reserved.)

Those of us with respiratory issues, severe asthma, for example, could see things exasperated if you spend a significant amount of time outside.

Today's current air quality (Copyright 2025 by KPRC Click2Houston - All rights reserved.)

The KPRC2 Weather Team will be monitoring the current air quality over the next few days to make sure you know what to expect if you’re feeling a little scratch to your eyes, nose, and throat.