September can be one of the nicest times of year to spend outside in Tennessee. Summer gradually begins giving way to fall; mornings can become more comfortable, and the first signs of the changing season start appearing across the landscape.
For people who experience seasonal allergies, however, September can bring something else: sneezing, congestion, itchy eyes, and runny noses. Spring may have the biggest reputation for pollen, but fall has its own collection of airborne allergens. Weed pollen, particularly ragweed, becomes an important seasonal trigger, while outdoor mold spores can remain abundant as leaves and other vegetation begin accumulating and decomposing.
For residents of Lakeland and the rest of Shelby County, understanding what is happening outdoors can help explain why allergy symptoms sometimes seem to return just as summer begins fading.
Ragweed Is a Major Fall Allergy Trigger
When people think about pollen, they often picture trees flowering during spring. Different types of plants, however, release pollen at different points during the year.
Tree pollen is typically associated with early spring, while grasses are more prominent during late spring and early summer. By late summer and fall, weed pollen becomes an important source of seasonal allergens.[1]
Ragweed is particularly significant. The American Academy of Allergy, Asthma & Immunology identifies ragweed pollen as the primary culprit behind many fall allergies. A single ragweed plant can produce enormous quantities of lightweight pollen that can become airborne and travel with the wind.[2] That means people do not necessarily need to have ragweed growing directly in their yards to encounter its pollen. Ragweed season generally begins during July or August in much of the country and continues until the first hard frost. In Tennessee, that puts September firmly within the period when ragweed pollen can be present.
Why Pollen Can Travel So Easily
Not every flowering plant creates the same allergy concerns. Many colorful garden flowers rely heavily on insects to move their pollen. Wind-pollinated plants operate differently. They produce lightweight pollen that can travel through the air, increasing the likelihood that people will breathe it in. This helps explain why removing a single weed from the backyard cannot necessarily eliminate someone’s exposure to seasonal pollen.
Weather also plays an important role.
Hot, dry, and windy conditions can help pollen travel, while rainy, cloudy, or calm conditions may temporarily reduce the amount moving through the air.[3] Conditions can therefore change noticeably from one day to the next. That is one reason someone may feel comfortable outdoors one afternoon and notice much stronger symptoms a few days later, even though the season has not changed.
Mold Can Be Part of the Fall Allergy Picture
Pollen is only one potential outdoor allergen during fall. Molds are fungi that produce tiny spores capable of becoming airborne. Outdoors, molds can be found around soil, plants, rotting wood, and other organic material. Unlike some pollen sources with relatively defined seasons, mold spores can remain present for long periods. The AAAAI notes that outdoor mold spores generally increase as temperatures rise during spring and can be found year-round in the South.[4]
Fall can create plenty of places for mold to thrive. Leaves fall from trees, grass clippings accumulate, gardens begin dying back, and piles of organic material remain damp after rain. Decomposing vegetation can provide an environment for mold growth. For someone sensitive to mold, a pile of wet leaves can therefore be more than a yard-maintenance issue.
Falling Leaves Aren’t Necessarily the Allergen
It is easy to say someone is “allergic to leaves,” but the situation is often more complicated. The leaf itself may not be the main problem. As fallen leaves become damp and begin decomposing, mold can grow on the organic material. Moving or raking those leaves can disturb mold spores and other particles and send them into the air.
The AAAAI specifically advises people with mold allergies to avoid raking leaves when possible because the activity can increase exposure to airborne mold.[5]
The same principle can apply to other fall yard work. Mowing, clearing garden beds, moving compost, and handling decaying vegetation can disturb particles that have accumulated outdoors. This does not mean yards should be left untouched all fall. It simply helps explain why someone might notice more sneezing or itchy eyes after spending an afternoon cleaning up leaves.
September Weather Can Make a Difference
West Tennessee’s September weather can still feel like summer on some days, and weather conditions can affect how much pollen is moving through the air. Dry weather allows pollen to remain airborne more easily, while wind can transport it across significant distances. Rain may temporarily wash some pollen from the air, although the relationship between rainfall and allergens is more complicated than simply assuming rain eliminates the problem.
The Asthma and Allergy Foundation of America notes that hot, dry conditions can contribute to pollen remaining airborne and traveling more easily. Rain and humidity can also influence other environmental allergens, including mold.[6] As a result, allergy conditions are not necessarily identical throughout September. A dry, breezy afternoon may produce a different outdoor environment from a cool morning following steady rain.
Fall Allergies Can Look a Lot Like Other Problems
Seasonal allergic rhinitis, commonly called hay fever, can produce symptoms including sneezing, nasal congestion, runny nose, and itching involving the nose, throat, eyes, or ears. But those symptoms do not automatically mean a person has a pollen allergy.
The AAAAI notes that rhinitis can also be associated with year-round allergens such as pets and dust mites. Smoke, pollution, strong odors, and changes in temperature or humidity can produce symptoms of non-allergic rhinitis as well.[7]
That distinction can become particularly confusing during fall, when seasonal allergens overlap with changing weather and the beginning of cold and respiratory-virus season.
Someone experiencing persistent or concerning symptoms should rely on an appropriate health professional for diagnosis rather than assuming ragweed, mold, or another specific allergen is responsible.
Indoor Allergens Don’t Disappear in the Fall
Spending more time indoors does not necessarily eliminate allergy triggers. Dust mites, pet allergens, cockroach particles, and indoor molds can contribute to year-round allergic rhinitis in susceptible individuals. Some people can experience both perennial allergies and seasonal flare-ups, meaning symptoms may become more noticeable when outdoor allergens are added to existing indoor exposures.[8]
Fall is also a useful time for homeowners to look for moisture problems.
Leaks around roofs, plumbing, or other areas can create damp environments where mold may grow. Basements, bathrooms, and other poorly ventilated spaces can be particularly susceptible to moisture. Keeping a home dry and addressing leaks is useful household maintenance regardless of whether anyone in the family has allergies.
Paying Attention to Pollen and Mold Counts
One way to better understand changing outdoor conditions is to follow pollen and mold information. The National Allergy Bureau, operated through the AAAAI, maintains a network of certified pollen and mold counting stations. These counts measure allergens collected from the air and can provide information about current conditions in participating regions.[9]
It is important to distinguish an actual pollen count from a pollen forecast. Counts reflect measured conditions, while forecasts may rely on historical pollen information and weather predictions. Residents may find it useful simply to notice patterns between outdoor conditions and their own experiences. Does a particular time of year seem to bring the same problems? Do symptoms become more noticeable after yard work? Are windy days different from calm ones? Those observations cannot diagnose an allergy, but they can provide useful context.
Fall Is Still a Great Time to Be Outside
Seasonal allergens do not change the fact that fall can be one of the most enjoyable times of year in Tennessee. For Lakeland residents, September and October bring opportunities for walking, gardening, attending community events, visiting parks, and simply spending more time outdoors as temperatures gradually become more comfortable. The important thing is understanding that spring does not have a monopoly on seasonal allergies. September sits at the intersection of several environmental changes. Ragweed and other weeds are releasing pollen, outdoor mold remains present, leaves begin accumulating, and weather conditions can change quickly.
For people who notice the same sneezing, congestion, or itchy eyes returning around this time each year, the changing Tennessee landscape may provide part of the explanation. Fall allergies are ultimately another reminder of just how much the natural environment changes from season to season — even when those changes are too small to see.
[1] American Academy of Allergy, Asthma & Immunology, “Outdoor Allergens.” https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/outdoor-allergens-ttr
[2] American Academy of Allergy, Asthma & Immunology, “Ragweed Plants Packed With Pollen.” https://www.aaaai.org/Aaaai/media/MediaLibrary/PDF%20Documents/Libraries/EL-ragweed-patient.pdf
[3] American Academy of Allergy, Asthma & Immunology, “Outdoor Allergens: Effects of Weather and Location.” https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/outdoor-allergens-ttr
[4] American Academy of Allergy, Asthma & Immunology, “Mold Allergy.” https://www.aaaai.org/conditions-treatments/allergies/mold-allergy
[5] American Academy of Allergy, Asthma & Immunology, “Mold Allergy: Treatment and Management.” https://www.aaaai.org/conditions-treatments/allergies/mold-allergy
[6] Asthma and Allergy Foundation of America, “How Does Rain Affect Pollen Levels?” https://community.aafa.org/blog/how-does-rain-affect-pollen-levels
[7] American Academy of Allergy, Asthma & Immunology, “Hay Fever/Rhinitis.” https://www.aaaai.org/conditions-treatments/allergies/hay-fever-rhinitis
[8] American Academy of Allergy, Asthma & Immunology, “Allergic Rhinitis: Reducing Allergen Exposure in a Changing Environment.” https://www.aaaai.org/tools-for-the-public/conditions-library/allergies/allergic-rhinitis
[9] American Academy of Allergy, Asthma & Immunology, “National Allergy Bureau.” https://www.aaaai.org/global/nab-pollen-counts
