Denver, CO Ragweed Pollen
Ragweed pollen in Denver usually peaks around September, reaching Very High at its worst. Denver's mile-high, dry climate shapes a distinct allergy year: mountain juniper on warm late-winter days, cottonwood in spring, grass through summer, and ragweed in fall.
Ragweed peaks from late summer into September along the Front Range.
Ragweed in Denver today
Monday, July 27, 2026
Ragweed pollen by month in Denver
How ragweed usually runs across the year. The current month is outlined.
Managing ragweed season in Denver
If ragweed is your trigger, start a daily antihistamine like cetirizine (Zyrtec) or loratadine (Claritin) a week or two before the September peak, rather than waiting for symptoms. Keep windows closed on high-count mornings, shower and change clothes after time outside, and run the AC on recirculate in the car.
When symptoms don't ease with over-the-counter medicine, an allergist in Colorado can test whether ragweed is really what you react to and talk through longer-term options like allergy shots.
Sources
More pollen in Denver
- Denver grass pollen — peaks June.
- Denver sagebrush pollen — peaks August to September.
- Denver cottonwood pollen — peaks April to May.
- Denver juniper pollen — peaks March to April.
- Denver pollen calendar — every allergen, month by month.
- Denver pollen count today — live tree, grass, and weed levels with a 5-day forecast.
- Colorado pollen season — the statewide calendar and other cities.
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Sign up for free alertsSeasonal pattern based on Colorado pollen data and local sources. Today's reading updated daily. MyPollenPal