Allergy season is “earlier, longer and worse” in these U.S. cities, reports show

(NEXSTAR) — That extra head congestion you’ve been feeling lately may not be all in your head, so to speak.

A new report on seasonal allergies found that the growing season has been extended by more than two weeks on average. A longer growing season means more days of sniffling, sneezing and headaches for allergy sufferers.

Climate Central, an organization of scientists and journalists dedicated to studying the impacts of climate change and global warming, has analyzed temperature data from 203 U.S. cities since 1970.

They found that the allergy season is not only getting longer, but also more intense.

It’s largely because warming temperatures have essentially shortened the length of freezing winters and extended the length of seasons in which allergen-producing plants thrive.

“Earlier spring and longer periods of frost-free days mean plants have more time to bloom and release allergy-inducing pollen,” Climate Central wrote in its report.

Of the 203 cities analyzed, 172 (about 85%) saw frost-free seasons lengthen – many by more than a month.

The cities where allergy season has grown the most since 1970, according to the report, are:

1. Reno, Nevada: 99 days longer
2. Bend, Oregon: 83 days longer
3. Las Cruces, New Mexico: 72 days longer
4. Medford, Oregon: 63 days longer
5. Boise, Idaho: 52 days longer
6. Tupelo, Mississippi: 51 days longer
7. El Paso, Texas: 50 days longer
8. Myrtle Beach, South Carolina: 46 days longer
9. Toledo, Ohio: 45 days longer
10. Wheeling, West Virginia: 44 days longer
11. Missoula, Montana: 42 days longer
12. Albuquerque, New Mexico: 39 days longer
13. Concord, New Hampshire: 39 days longer
14. Eugene, Oregon: 38 days longer
15. Jefferson City, Missouri: 38 days longer

The Centers for Disease Control and Prevention agrees that climate change may cause people to experience more health consequences from allergens. Pollen exposure can lead to symptoms of hay fever and allergic conjunctivitis, and can lead to more asthma attacks in people with asthma.

There were some cities among the 203 cities analyzed where the growing season is getting shorter, Climate Central scientists found. Ottumwa, Iowa; Denver, Colorado; and Waco, Texas all saw their growing season shortened by 15 days or more.