Ragweed season begins as early as July and lasts until the first hard frost, according to the American Academy of Allergy, Asthma and Immunology. Individuals who are allergic to ragweed often experience increased sneezing and congestion during this time period.
Ragweed pollen is too tiny to see and nearly impossible to avoid entirely. The pollen count is higher on windy days and in the early mornings when plants give off the allergen. Ragweed plants also emit more pollen as they dry after rain. Ragweed is found throughout the United States, but it is most prevalent in the Midwest and along the East Coast.