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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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 |
|---|---|---|---|
| Denver | Very Highas of Jul 15 | Grass | Moderate |
| Lakewood | Very Highas of Jul 15 | Grass | Moderate |
| Lafayette | Very Highas of Jul 15 | Grass | Moderate |
| Commerce City | Very Highas of Jul 15 | Grass | Moderate |
| Security-Widefield | Very Highas of Jul 15 | Grass | Moderate |
| Pueblo West | Very Highas of Jul 15 | Grass | Moderate |
| Erie | Very Highas of Jul 15 | Grass | Moderate |
| Four Square Mile | Very Highas of Jul 15 | Grass | Moderate |
| Louisville | Very Highas of Jul 15 | Grass | Moderate |
| Montrose | Very Highas of Jul 15 | Grass | Moderate |
| Sherrelwood | Very Highas of Jul 15 | Grass | Moderate |
| Fort Carson | Very Highas of Jul 15 | Grass | Moderate |
| Firestone | Very Highas of Jul 15 | Grass | Moderate |
| Canon City | Very Highas of Jul 15 | Grass | Moderate |
| Greenwood Village | Very Highas of Jul 15 | Grass | Moderate |
| Federal Heights | Very Highas of Jul 15 | Grass | Moderate |
| Castle Pines | Very Highas of Jul 15 | Grass | Moderate |
| The Pinery | Very Highas of Jul 15 | Grass | Moderate |
| Berthoud | Very Highas of Jul 15 | Grass | Moderate |
| Cherry Hills Village | Very Highas of Jul 15 | Grass | Moderate |
| Salida | Very Highas of Jul 15 | Grass | Moderate |
| Telluride | Very Highas of Jul 15 | Grass | Moderate |
| Buena Vista | Very Highas of Jul 15 | Grass | Moderate |
| Carbondale | Very Highas of Jul 15 | Grass | Moderate |
| Paonia | Very Highas of Jul 15 | Grass | Moderate |
| Idaho Springs | Very Highas of Jul 15 | Grass | Moderate |
| Estes Park | Very Highas of Jul 15 | Grass | Moderate |
| Delta | Very Highas of Jul 15 | Grass | Moderate |
| Colorado Springs | Highas of Jul 15 | Grass | Moderate |
| Pueblo | Highas of Jul 15 | Grass | Moderate |
| Westminster | Highas of Jul 15 | Grass | Moderate |
| Highlands Ranch | Highas of Jul 15 | Grass | Moderate |
| Broomfield | Highas of Jul 15 | Grass | Moderate |
| Parker | Highas of Jul 15 | Grass | Moderate |
| Dakota Ridge | Highas of Jul 15 | Grass | Moderate |
| Englewood | Highas of Jul 15 | Grass | Moderate |
| Ken Caryl | Highas of Jul 15 | Grass | Moderate |
| Wheat Ridge | Highas of Jul 15 | Grass | Moderate |
| Fountain | Highas of Jul 15 | Grass | Moderate |
| Columbine | Highas of Jul 15 | Grass | Moderate |
| Cimarron Hills | Highas of Jul 15 | Grass | Moderate |
| Welby | Highas of Jul 15 | Grass | Moderate |
| Frederick | Highas of Jul 15 | Grass | Moderate |
| Lone Tree | Highas of Jul 15 | Grass | Moderate |
| Superior | Highas of Jul 15 | Grass | Moderate |
| Monument | Highas of Jul 15 | Grass | Moderate |
| Westcliffe | Highas of Jul 15 | Grass | Moderate |
| Dolores | Highas of Jul 15 | Grass | Moderate |
| Fowler | Highas of Jul 15 | Grass | Moderate |
| Starkville | Highas of Jul 15 | Grass | Moderate |
| Salt Creek | Highas of Jul 15 | Grass | Moderate |
| Manitou Springs | Highas of Jul 15 | Grass | Moderate |
| Woodland Park | Highas of Jul 15 | Grass | Moderate |
| Evergreen | Highas of Jul 15 | Grass | Moderate |
| Hotchkiss | Highas of Jul 15 | Grass | Moderate |
| Elizabeth | Highas of Jul 15 | Grass | Moderate |
| Greeley | Moderateas of Jul 15 | Grass | Moderate |
| Thornton | Moderateas of Jul 15 | Grass | Moderate |
| Boulder | Moderateas of Jul 15 | Grass | Moderate |
| Centennial | Moderateas of Jul 15 | Grass | Moderate |
| Longmont | Moderateas of Jul 15 | Grass | Moderate |
| Loveland | Moderateas of Jul 15 | Grass | Moderate |
| Castle Rock | Moderateas of Jul 15 | Grass | Moderate |
| Littleton | Moderateas of Jul 15 | Grass | Moderate |
| Northglenn | Moderateas of Jul 15 | Grass | Moderate |
| Evans | Moderateas of Jul 15 | Grass | Moderate |
| Golden | Moderateas of Jul 15 | Grass | Moderate |
| Johnstown | Moderateas of Jul 15 | Grass | Moderate |
| Trinidad | Moderateas of Jul 15 | Grass | Moderate |
| Rockvale | Moderateas of Jul 15 | Grass | Moderate |
| Cortez | Moderateas of Jul 15 | Grass | Moderate |
| Palmer Lake | Moderateas of Jul 15 | Grass | Moderate |
| Mead | Moderateas of Jul 15 | Grass | Moderate |
| Cedaredge | Moderateas of Jul 15 | Grass | Moderate |
| Cahone | Moderateas of Jul 15 | Grass | Moderate |
| Conifer | Moderateas of Jul 15 | Grass | Moderate |
| Mancos | Moderateas of Jul 15 | Grass | Moderate |
| Nucla | Moderateas of Jul 15 | Grass | Moderate |
| Larkspur | Moderateas of Jul 15 | Grass | Moderate |
| Durango | Lowas of Jul 15 | Grass | Moderate |
| Monte Vista | Lowas of Jul 15 | Grass | Moderate |
| Fort Collins | Noneas of Jul 15 | None | Moderate |
| Grand Junction | Noneas of Jul 15 | None | Moderate |
| Windsor | Noneas of Jul 15 | None | Moderate |
| Clifton | Noneas of Jul 15 | None | Moderate |
| Black Forest | Noneas of Jul 15 | None | Moderate |
| Fruita | Noneas of Jul 15 | None | Moderate |
| Steamboat Springs | Noneas of Jul 15 | None | Moderate |
| Sterling | Noneas of Jul 15 | None | Moderate |
| Wellington | Noneas of Jul 15 | None | Moderate |
| Fort Morgan | Noneas of Jul 15 | None | Moderate |
| Burns | Noneas of Jul 15 | None | Moderate |
| Silt | Noneas of Jul 15 | None | Moderate |
| Falcon | Noneas of Jul 15 | None | Moderate |
| Elbert | Noneas of Jul 15 | None | Moderate |
| Wiggins | Noneas of Jul 15 | None | Moderate |
| Vail | Noneas of Jul 15 | None | Moderate |
| Gypsum | Noneas of Jul 15 | None | Moderate |
| Aspen | Noneas of Jul 15 | None | Moderate |
| Ovid | Noneas of Jul 15 | None | Moderate |
| Glenwood Springs | Noneas of Jul 15 | None | Moderate |
| Peyton | Noneas of Jul 15 | None | Moderate |
| Craig | Noneas of Jul 15 | None | Moderate |
| Fairplay | Noneas of Jul 15 | None | Moderate |
| Breckenridge | Noneas of Jul 15 | None | Moderate |
| Walden | Noneas of Jul 15 | None | Moderate |
| Basalt | Noneas of Jul 15 | None | Moderate |
| Frisco | Noneas of Jul 15 | None | Moderate |
| Silverthorne | Noneas of Jul 15 | None | Moderate |
| Avon | Noneas of Jul 15 | None | Moderate |
| Aurora | No live reading | Not available | Moderate |
| Arvada | No live reading | Not available | Moderate |
| Brighton | No live reading | Not available | Moderate |
| Hartsel | No live reading | Not available | Moderate |
| Pagosa Springs | No live reading | Not available | Moderate |
| Boyero | No live reading | Not available | Moderate |
| Winter Park | No live reading | Not available | Moderate |
| Franktown | No live reading | Not available | Moderate |
| Eaton | No live reading | Not available | Moderate |
| Timnath | 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.