Ragweed pollen count spikes each fall across the United States, affecting over 23 million people. A single ragweed plant can produce up to a billion pollen grains per season — and the wind carries them 400+ miles.
Peak season: Late July through October, peaking in mid-September
Most affected regions: Midwest, South, Mid-Atlantic, Northeast
Common symptoms: Sneezing, runny nose, itchy eyes, nasal congestion, post-nasal drip.
A ragweed pollen count above 50 grains per cubic meter is considered high. Above 500 is very high and can cause severe symptoms even in people with mild allergies.
Ragweed season typically ends after the first hard frost. In the South this can be as late as November; in northern states it usually ends by October.
Cities with consistently high ragweed pollen include Wichita KS, Louisville KY, Dayton OH, McAllen TX, Oklahoma City OK, and most cities in the Midwest and Mid-Atlantic.