You would think seasonal allergies are just that, seasonal. But climate change is already having an impact, affecting the length and strength of each season. In the US, allergies are typically caused by ragweed during the fall months (previously through October / early November). However, warmer fall weather and later frost seasons have now extended the fall allergy season into December in some areas. That’s not all. There is also evidence that climate change may be affecting the amount of pollen and how likely it is to cause an allergic reaction.
Which Pollen Allergies are Common in the Fall?
Ragweed pollen is one of the primary environmental allergens contributing to allergic rhinitis (hay fever) during the fall.
The 17 species of ragweed grow in most regions throughout the US, and it is estimated that 15.5 percent of Americans have a ragweed sensitivity, including around 23 million who are affected by hay fever (seasonal allergic rhinitis).
Maturing in the mid-summer, ragweed plants typically generate pollen for several months with peaks in late summer, early fall. However, rising temperatures seen in the United States seem to be extending how long ragweed plants continue to produce pollen.
According to a report by the United States Environmental Protection Agency (US EPA) and the National Allergy Bureau, examining 11 cities in central United States and Canada, ragweed pollen season is indeed increasing in length, particularly in the northern states and Canada – as higher latitudes in general are experiencing warming temperatures more rapidly than the rest of the world. In fact, the report documents an increase of ragweed season length by up to 25 days in some areas between 1995-2015.

Is Ragweed Season Getting Longer?
According to the EPA Climate Change Indicator report, the upward trend in the number of ragweed pollen days is strongly related to fall frosts, when ragweed plants typically stop producing pollen. As the climate changes, the first frost is being delayed until later in the year, particularly in northern areas. Whereas, at pollen stations located in southern states the frost season hasn’t changed as dramatically, so a smaller effect on ragweed pollen season can be seen at those stations.
With warmer fall temperatures, a longer growing season and later frost season, many areas are experiencing longer allergy seasons. When you add to the fact that spring allergy season is starting earlier, there is a chance that those sensitive to multiple types of pollen will experience allergy symptoms almost all-year round.
Read More: Allergy Season Isn’t Really Seasonal Anymore: Here’s Why
Are Fall Allergies Getting More Severe?
Although there are several factors that can affect changes in pollen seasons and severity, the data indicates that climate change is definitely making an impact on fall allergies.
Not only has fall allergy season been extended in several locations throughout the US, according to some studies the pollen itself is more allergenic and being produced in larger quantities. This is in part due to the warmer temperatures and increased carbon dioxide levels. In fact, researchers predict that the US could see as much as a 200% increase in pollen this century if greenhouse gas emissions continue at the current rate.
Read more about this: Is Pollen Increasing Due To Climate Change?
Understanding Ragweed Pollen Impact + Hay Fever Fall Allergy Symptoms
Most of the symptoms of fall allergies and sensitivity to ragweed are similar to other pollen allergies, including:
- Sneezing
- Runny Nose
- Congestion
- Headaches
- Eye Irritation
- Scratchy Throat
Pollen from ragweed can also trigger asthma attacks and symptoms, causing wheezing and coughing. Ragweed can also trigger ‘Oral Allergy Syndrome’ that causes an itchy and/or swollen mouth, throat, lips, and tongue.
Monitoring Ragweed Pollen Counts
Unlike pollen produced by grasses and trees during spring and summer allergy seasons, which peaks in volume in the evening, fall allergy pollen usually has the highest count in the morning. For allergy sufferers in the autumn, the more information they have about current and forecast pollen levels the better. This way they can plan their activities and take precautions to reduce exposure. (Pollen counts and forecasts can be checked using BreezoMeter’s Live Map).
To deliver accurate and timely pollen forecasts, BreezoMeter leverages sophisticated AI-driven data analysis and prediction methods. We layer this with data about vegetation land cover, climate, and weather conditions – all of which serve to inform our pollen forecasting models.
Our unique approach to pollen forecasting not only better empowers individual sufferers, it also helps healthcare providers overcome some of the challenges of seasonal unpredictability by providing timely insights into where and when to adjust medicine supply, advertising spend, and their messaging.
As BreezoMeter’s pollen reporting is broken down by pollen species and plant, consumer brands are also more empowered to personalize their experiences and recommendations based on an individual’s sensitivity to a particular type of pollen such as Ragweed.

Tracking Ragweed Pollen with BreezoMeter’s Pollen API
Top brands and healthcare providers from several industries rely on BreezoMeter’s pollen data to provide their customers with crucial personalized information to improve their health in relation to pollen allergies. Our data and insights are used to create loyal and engaged customers, dynamically optimize advertising campaigns, and to better understand patient behavior and health.
Read about 10 Reasons to Integrate Pollen Data or check out the following case studies:
- Allergy medication companies like ALK have used our data to better educate and engage end users of klarify.me and experienced a 50% decrease in churn.
- Hikers can avoid air pollution and areas with high pollen count using the Alltrails app, which integrates BreezoMeter’s data.
“With air pollution becoming an increased health concern, this data is integral to informing our users of local air quality conditions and keeping outdoor enthusiasts healthy while out on the trails”
AllTrails CMO Ron Schneidermann
- Propeller Health uses air quality and pollen data for a connected inhaler that resulted in 84% fewer asthma symptoms.
- Japan has the highest levels of diagnosed allergic rhinitis in the world, prompting Taisho to launch a brand new digital experience providing seasonal allergy sufferers with live and forecast pollen conditions at their current location or wherever they plan to go.
Learn more about BreezoMeter’s Pollen API and the benefits of integrating pollen data and insights into your business:
