Leominster Mold Forecast
Mold Today
Today (20 September) mold in Leominster is low; alternaria and cladosporium are low.
Mold Tomorrow
Tomorrow (21 September 2026) alternaria remains low, cladosporium increasing.
7-Day Trend
Over the next week alternaria and cladosporium will decrease.
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Mold Risk
Today - 20 September
| Mold species | Level | Value |
|---|---|---|
| Alternaria | Low | 3/100 |
| Cladosporium | Low | 13/100 |
Tomorrow - 21 September
| Mold species | Level | Value | 7-Day Trend |
|---|---|---|---|
| Alternaria | Low | 13/100 | Decreasing |
| Cladosporium | Moderate | 38/100 | Decreasing |
Local Mold Conditions
Both moisture and temperature matter for mold growth, and Leominster averages 61.2% soil moisture in a temperate climate where the two need to overlap for conditions to be truly favourable. Organic matter, a key substrate for both species, is typically available in abundance. These conditions favour Alternaria in particular, while Cladosporium grows more steadily but less vigorously.
Mold in Leominster tracks the overlap of warmth and moisture — both need to align, and those peaks don't always coincide. The peak of 68.5% in April and the low in December define the moisture range — the active mold season falls where those higher levels meet sufficient warmth. Both species disperse spores in wind rather than rain — so the highest airborne counts follow the moisture peak rather than coinciding with it.
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Pollen forecast neighborhoods 2 neighborhoods
Sports venues in Leominster 2 sports venues
Frequently Asked Questions About Mold in Massachusetts
Why do I still have allergy symptoms after the pollen season?
Allergy symptoms after the main pollen season may be caused by mold spores. Outdoor mold levels can remain high into late summer and autumn, when pollen levels are already falling. Mold allergy can cause symptoms similar to pollen allergy, including sneezing, a runny or blocked nose, itchy eyes, coughing, and wheezing.
What are mold spores and why do they cause allergies?
Mold spores are tiny particles released by fungi into the air. When inhaled, they can trigger an allergic reaction in sensitive people. Common symptoms include sneezing, a runny or blocked nose, itchy or watery eyes, coughing, and wheezing.
When are mold spore levels highest?
Outdoor mold spore levels often increase during warm and humid conditions, particularly when there is plenty of decaying vegetation. Levels can vary considerably with weather, season, vegetation, and location, and some types of mold are more common during particular times of the year, e.g. in the Fall.
How can I reduce my exposure to mold spores?
If you are sensitive to mold, check local mold spore levels and forecasts before spending long periods outdoors. On high-risk days, reducing time around dense vegetation, compost, fallen leaves, and other sources of decaying plant material may help limit exposure.
Understanding the Scale
The 0–100 scores represent risk levels, not direct measurements of pollen or air pollutant concentrations. Higher scores indicate higher risk. Pollen and air quality use different thresholds.
Mold
| None | 0 | No or negligible risk of exposure. Pollen/mold exposure is expected to be minimal. |
| Low | 0-25 | Low risk of exposure. Small amounts of pollen or mold spores may be present. |
| Moderate | 25-50 | Moderate risk of exposure. Pollen/mold exposure is expected to be noticeable. |
| High | 50-75 | High risk of exposure. Elevated pollen/mold exposure is expected. |
| Very High | 75-100 | Very high risk of exposure. Pollen/mold exposure is expected to be at or near its highest levels. |
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Get 15-day pollen forecasts with morning, afternoon and evening detail, plus 5-day air quality forecasts. Explore interactive pollen risk maps, estimated pollen season start, route profiles and a symptoms diary.
Features and forecast availability vary by region. Currently covering Europe, the contiguous US, southern Canada, South Africa, Australia, Indonesia (Java & Bali), Brazil, Paraguay, Uruguay and the Buenos Aires area.
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