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Official Website

of the Commonwealth of Pennsylvania

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    Amount of Pollen in the Air

    Because ragweed is a local problem, use the following information to help determine what ragweed levels can be found in your area.

    1. Weather conditions - Dry, windy, sunny weather is the ultimate conditions for pollen dispersal whereas rainy weather will scrub pollen from the air.

    2. Time of Year - In general, ragweed pollen dispersal in Pennsylvania peaks the last week of August and the first week of September. 

    3. Geographic Location - Ragweed grows best in disturbed soils. Based on the percentage of farmland in each county, the map below suggests where ragweed may be the most concentrated. 

    Pollen Counts During August and September

    4. Time of Day - Ragweed pollen release peaks in the morning hours between 5 and 10 o'clock.

    Farmland Percentages by County