Colorado pollen and allergy seasons
July outlookModerate
Colorado has a spring tree season along the Front Range and a strong late summer weed season led by ragweed and sagebrush.
Twelve month pollen calendar
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F
M
A
M
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A
S
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D
LowModerateHighVery high
Dominant species in July
Grass
Typical peak in July
No clear peak this month
Worst month of the year
September
Best month of the year
January
What is active in July
Grass
Cities in Colorado
| City | Today | Worst today | Typical in July |
|---|---|---|---|
| Colorado Springs | Very Highas of Jul 12 | Grass | Moderate |
| Lakewood | Very Highas of Jul 12 | Grass | Moderate |
| Westminster | Very Highas of Jul 12 | Grass | Moderate |
| Lafayette | Very Highas of Jul 12 | Grass | Moderate |
| Ken Caryl | Very Highas of Jul 12 | Grass | Moderate |
| Lone Tree | Very Highas of Jul 12 | Grass | Moderate |
| Castle Pines | Very Highas of Jul 12 | Grass | Moderate |
| Paonia | Very Highas of Jul 12 | Grass | Moderate |
| Evergreen | Very Highas of Jul 12 | Grass | Moderate |
| Manitou Springs | Very Highas of Jul 12 | Grass | Moderate |
| Starkville | Very Highas of Jul 12 | Grass | Moderate |
| Telluride | Very Highas of Jul 12 | Grass | Moderate |
| Palmer Lake | Very Highas of Jul 12 | Grass | Moderate |
| Salida | Very Highas of Jul 12 | Grass | Moderate |
| Wellington | Noneas of Jul 12 | None | Moderate |
| Fort Morgan | Noneas of Jul 12 | None | Moderate |
| Silt | Noneas of Jul 12 | None | Moderate |
| Winter Park | Noneas of Jul 12 | None | Moderate |
| Ovid | Noneas of Jul 12 | None | Moderate |
| Denver | No live reading | Not available | Moderate |
| Aurora | No live reading | Not available | Moderate |
| Fort Collins | No live reading | Not available | Moderate |
| Greeley | No live reading | Not available | Moderate |
| Thornton | No live reading | Not available | Moderate |
| Grand Junction | No live reading | Not available | Moderate |
| Arvada | No live reading | Not available | Moderate |
| Boulder | No live reading | Not available | Moderate |
| Pueblo | No live reading | Not available | Moderate |
| Centennial | No live reading | Not available | Moderate |
| Longmont | No live reading | Not available | Moderate |
| Highlands Ranch | No live reading | Not available | Moderate |
| Loveland | No live reading | Not available | Moderate |
| Castle Rock | No live reading | Not available | Moderate |
| Broomfield | No live reading | Not available | Moderate |
| Commerce City | No live reading | Not available | Moderate |
| Parker | No live reading | Not available | Moderate |
| Littleton | No live reading | Not available | Moderate |
| Brighton | No live reading | Not available | Moderate |
| Security-Widefield | No live reading | Not available | Moderate |
| Northglenn | No live reading | Not available | Moderate |
| Windsor | No live reading | Not available | Moderate |
| Pueblo West | No live reading | Not available | Moderate |
| Dakota Ridge | No live reading | Not available | Moderate |
| Englewood | No live reading | Not available | Moderate |
| Wheat Ridge | No live reading | Not available | Moderate |
| Erie | No live reading | Not available | Moderate |
| Fountain | No live reading | Not available | Moderate |
| Columbine | No live reading | Not available | Moderate |
| Evans | No live reading | Not available | Moderate |
| Four Square Mile | No live reading | Not available | Moderate |
| Louisville | No live reading | Not available | Moderate |
| Montrose | No live reading | Not available | Moderate |
| Golden | No live reading | Not available | Moderate |
| Clifton | No live reading | Not available | Moderate |
| Sherrelwood | No live reading | Not available | Moderate |
| Durango | No live reading | Not available | Moderate |
| Cimarron Hills | No live reading | Not available | Moderate |
| Fort Carson | No live reading | Not available | Moderate |
| Johnstown | No live reading | Not available | Moderate |
| Firestone | No live reading | Not available | Moderate |
| Canon City | No live reading | Not available | Moderate |
| Welby | No live reading | Not available | Moderate |
| Frederick | No live reading | Not available | Moderate |
| Greenwood Village | No live reading | Not available | Moderate |
| Black Forest | No live reading | Not available | Moderate |
| Federal Heights | No live reading | Not available | Moderate |
| Fruita | No live reading | Not available | Moderate |
| Steamboat Springs | No live reading | Not available | Moderate |
| Sterling | No live reading | Not available | Moderate |
| Superior | No live reading | Not available | Moderate |
| The Pinery | No live reading | Not available | Moderate |
| Berthoud | No live reading | Not available | Moderate |
| Wiggins | No live reading | Not available | Moderate |
| Timnath | No live reading | Not available | Moderate |
| Cherry Hills Village | No live reading | Not available | Moderate |
| Monte Vista | No live reading | Not available | Moderate |
| Elizabeth | No live reading | Not available | Moderate |
| Delta | No live reading | Not available | Moderate |
| Silverthorne | No live reading | Not available | Moderate |
| Hotchkiss | No live reading | Not available | Moderate |
| Estes Park | No live reading | Not available | Moderate |
| Idaho Springs | No live reading | Not available | Moderate |
| Larkspur | No live reading | Not available | Moderate |
| Frisco | No live reading | Not available | Moderate |
| Nucla | No live reading | Not available | Moderate |
| Trinidad | No live reading | Not available | Moderate |
| Rockvale | No live reading | Not available | Moderate |
| Mancos | No live reading | Not available | Moderate |
| Conifer | No live reading | Not available | Moderate |
| Cahone | No live reading | Not available | Moderate |
| Monument | No live reading | Not available | Moderate |
| Basalt | No live reading | Not available | Moderate |
| Woodland Park | No live reading | Not available | Moderate |
| Walden | No live reading | Not available | Moderate |
| Breckenridge | No live reading | Not available | Moderate |
| Fairplay | No live reading | Not available | Moderate |
| Salt Creek | No live reading | Not available | Moderate |
| Craig | No live reading | Not available | Moderate |
| Hartsel | No live reading | Not available | Moderate |
| Burns | No live reading | Not available | Moderate |
| Cedaredge | No live reading | Not available | Moderate |
| Carbondale | No live reading | Not available | Moderate |
| Buena Vista | No live reading | Not available | Moderate |
| Eaton | No live reading | Not available | Moderate |
| Cortez | No live reading | Not available | Moderate |
| Fowler | No live reading | Not available | Moderate |
| Franktown | No live reading | Not available | Moderate |
| Falcon | No live reading | Not available | Moderate |
| Mead | No live reading | Not available | Moderate |
| Peyton | No live reading | Not available | Moderate |
| Glenwood Springs | No live reading | Not available | Moderate |
| Elbert | No live reading | Not available | Moderate |
| Dolores | No live reading | Not available | Moderate |
| Aspen | No live reading | Not available | Moderate |
| Boyero | No live reading | Not available | Moderate |
| Gypsum | No live reading | Not available | Moderate |
| Vail | No live reading | Not available | Moderate |
| Pagosa Springs | No live reading | Not available | Moderate |
| Westcliffe | No live reading | Not available | Moderate |
Today and worst today come from live readings where available. Typical shows the usual level for this month from the seasonal profile.
The Colorado allergy season
Allergy levels in Colorado peak in September, when ragweed pollen runs highest. The season moves through tree pollen around March, grass in June, weed pollen such as ragweed in September. Levels start to climb around March. The lowest pollen levels of the year arrive in January.
Common questions
When does allergy season start in Colorado?
Pollen levels in Colorado usually begin climbing in March and reach their highest point in September.
What is the worst month for allergies in Colorado?
September is typically the worst month in Colorado, driven by ragweed pollen.
When does ragweed season end in Colorado?
Ragweed pollen in Colorado usually fades by the end of October, after the first hard frost in colder areas.
When is the best time for allergies in Colorado?
January usually brings the lowest pollen levels of the year in Colorado.