High Pollen in Thornton, CO
High today, mostly weed pollen.
Last updated August 15, 2026
What to do today
- Avoid mowing the lawn and raking leaves.
- When driving the car, close your windows and turn the air conditioning system to recirculation mode.
- Keep your windows closed and turn on your air purifier or air conditioning.
- Consider staying indoors during the peak pollen hours (morning and early afternoon).
Forecast
About pollen in Thornton
Weed pollen is running high in Thornton today and is the main driver of allergy symptoms across the area. Anyone sensitive to ragweed and similar late-summer weeds should expect noticeable effects, from sneezing to itchy eyes, especially during the afternoon when pollen tends to circulate most freely outdoors. Tree pollen is a non-issue right now, so any discomfort you're feeling is almost certainly weed-related. Looking ahead, weed pollen is expected to stay elevated over the next several days, even climbing slightly higher by midweek before easing a bit toward the weekend. This tracks with the usual late-summer pattern in the Front Range, when ragweed and other weeds take over as the dominant allergen after cottonwoods, oaks, and other spring-blooming trees have long finished releasing pollen. If you're prone to weed allergies, this is a good stretch to be a little more mindful, since conditions aren't likely to let up soon.
Common questions
- What is the pollen count in Thornton, CO today?
- Thornton, CO is at a high 4 out of 5 on the Universal Pollen Index today, driven mainly by weed pollen. Over the next five days it ranges from 4 to 5 of 5.
- Is weed pollen high in Thornton, CO right now?
- Weed pollen is high today at 4 of 5, and it's past its peak season. Many allergy sufferers will have symptoms.
- What plants are causing allergies in Thornton, CO?
- Elm (Ulmaceae (the Elm family), Two distinct seasons, late winter to early spring, and late summer to fall (species dependent)) is actively pollinating.