Skip to content


    2021 Ragweed Season Begins

    2021 Ragweed Season Begins

     Ragweed season has begun in United States with Olean, New York, a National Allergy Bureau certified pollen counting station reporting ragweed pollen release over the past week along with Kean University in Union New, Jersey and in Springfield, New Jersey. “The forecast is for ragweed pollen to be released in increasing concentrations in the New York/New Jersey metropolitan this coming week.” As reported by Dr. Leonard Bielory, Chairman of the National Allergy Bureau.  “Historically, over the past 5 years the highest ragweed pollen count has occurred in mid-August. This has been the latest onset we have seen in a while, but the peak will quite high in the coming weeks due to the heavy rain precipitation we have had over the summer.” Dr. Bielory said.

    Three out 4 Americans who have allergies are allergic to ragweed pollen. The affect of weather patterns has a strong impact on pollination. “The peak on ragweed pollination usually occurs now, but ragweed will continue pollenate till the first frost”. The monitoring of the real pollen count regularly performed in Dr. Bielory’s lab as he has been focusing his research on the impact of climate change weather patterns on pollen release triggering allergic airway disorders such as asthma, allergic conjunctivitis and allergic rhinitis.  Dr. Bielory has also recently reported in the Proceedings on the National Academy of Sciences on the changes in “pollen seasons” actually increasing and potential effect on the COVID-19 infections.

    As part of an ongoing study by Dr. Leonard Bielory and the researchers at Rutgers University and the U.S. Department of Agriculture, funded in part by the U.S. Environmental Protection Agency.  A changing climate means allergy-causing ragweed pollen has a longer season that extends further north than it did just 16 years ago and in New Jersey appears to increasing in duration of exposure. Dr. Bielory and other allergy experts found that ragweed pollen season lasted as much as 27 days longer in 2009 than it did in 1995 with increasing range northward resulting in a more dramatic the change in the length of pollen season. Allergies associated with ragweed pollen (to which 3 out of 4 Americans who are allergic have ragweed allergies – also known as hay fever) costs about $21 billion a year in the United States. At one time this was hypothesized and modeled as a possibility – “but it is a reality” according to Leonard Bielory, M.D. who was the principal investigator of the U.S. EPA – “this is affecting patients now!” Ragweed is not the only pollen season affected as the study has shown the impact on tree and grass pollen seasons that occur n the early and late spring. Dr. Bielory is continuing his work on examining other species and other regions of the continental United States.

    As global average temperatures have warmed, the first frost has been delayed, especially at higher latitudes, which has meant a longer season for ragweed. Because warming is greater at these high latitudes, the length of the season has been more pronounced.

    From the report the ragweed season actually shrank by 4 days between 1995 and 2009 in Texas while further north it was noted to be 11 days longer in Nebraska; 16 days longer in Minnesota; and 27 days Saskatchewan in Canada. In New Jersey, the season appears to have increased over the past 20 years, but not as prolonged as the differences noted in Canada. This appears to eventually impact on the diagnosis of allergies that could coincide with the flu season. Primary care physicians may under-diagnose and undertreat allergies since they would not be familiar with such a change in the allergy season and thus may require the assistance of an allergist to confirm the diagnosis to maximize the treatment for their patients. 

    Hot and dry weather in source areas aid the release of ragweed pollen during the flowering season and result in the deep distribution needed to lift the pollen over the greater dispersion.

    "Allergies that have been minor in the past are going to increase and become more of a clinical problem that may also impact patients with asthma!” Bielory said.  

    Additional Points 

    For the actual pollen count one can download the free AccuPollen® mobile app based upon participants in the PollenUnderGround®