What to Expect During Fall Allergy Season

While autumn brings to mind images of crisp weather, changing leaves, and high school football games, for some, it is the time to prepare for the onset of the dreaded fall allergy season.

Woman blowing nose, fall scene
Guido Mieth / Moment / Getty Images

While people tend to associate seasonal allergies with spring (and things like tree pollen), there are those who only suffer during the autumn months. For these people, the chief culprits are not trees but common grasses and weeds, particularly ragweed.

Fall Pollen Allergies

Weed pollen is the main cause of hay fever (allergic rhinitis) during the late summer and early fall months. Depending on where you live in North America, the main allergen concerns include:

  • Ragweed
  • Sagebrush
  • Pigweed
  • Tumbleweed
  • Russian thistle
  • Cocklebur
  • Burning bush
  • Lamb’s-quarters
  • Mugwort

While the severity of an allergy season can vary by seasonal climate, there can be days (and even times of day) when the allergy risk is high. This includes windy and warm days when pollen counts can soar. By contrast, rainy days can significantly reduce the pollen count (only to give rise to higher counts when the grasses dry out).

Along with grasses and weeds, mold is a major cause of fall allergies. This is especially true in areas where large piles of damp leaves are allowed to sit and rot.

All About Ragweed

Ragweed is, by far, the leading cause of allergy in the autumn months. The ragweed season can vary but tends to begin in August and continue right through to November in some areas.

The plant thrives in areas where there are cool nights and warm days. While ragweed can pretty much be found in every part of the U.S. (including Hawaii and Alaska), it is most prevalent in the Midwest and on the East Coast where the peak season runs until early- to mid-September.

As with other grass allergies, the pollen is highest during the morning hours, on windy days, and shortly after a rainstorm. Ragweed can grow just about everywhere but can proliferate in fields, along the side of the road, or in vacant lots.

How to Avoid Fall Allergies

Avoiding fall allergies is often easier said than done. After all, with work, family, and a social life, you can't shut yourself in with antihistamines and a box of tissues.

Instead, you have to be strategic in how you approach allergy season by taking certain, basic precautions. Among them:

  • Check the local pollen and mold counts on the daily weather report.
  • Keep your windows and doors shut at home, especially on days when the pollen count is high.
  • Shut the car windows and air vents when driving.
  • Use a HEPA filter and/or air humidifier to keep airborne pollen levels low.
  • Vacuum floors, surfaces, and furniture regularly, ideally with a pet-friendly vacuum cleaner designed to suck up dust, dander, mites, and other tiny particles.
  • Wear a NIOSH-rated 95 filter mask when mowing the lawn or doing outdoor work.
  • Take a shower and change your clothes after you’ve worked or played outdoors.

Finally, if you have a history of fall allergy symptoms, speak with your healthcare provider or allergist about daily medications or allergy shots you can take to lessen the impact of the season. While allergy shots typically need to be started a few months before your worst allergy season(s) in order to best deter symptoms, nasal corticosteroid sprays work within a couple of weeks and antihistamines work within minutes.

3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American College of Allergy, Asthma, and Immunology. Common seasonal allergy triggers.

  2. American College of Asthma, Allergy, and Immunology. Ragweed allergy.

  3. Terrie YC. How can patients prevent and treat fall allergies. Pharmacy Times.

By Daniel More, MD
Daniel More, MD, is a board-certified allergist and clinical immunologist. He is an assistant clinical professor at the University of California, San Francisco School of Medicine and currently practices at Central Coast Allergy and Asthma in Salinas, California.