Yorktown, Philadelphia Mold Forecast - Today, Tomorrow and the Week Ahead
Mold Today
Today (10 October) mold in Yorktown, Philadelphia is low; alternaria and cladosporium are low.
Mold Tomorrow
Tomorrow (11 October 2026) levels are similar to today.
7-Day Trend
Over the next week alternaria and cladosporium will increase.
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Mold Risk
Today - 10 October
| Mold species | Level | Value |
|---|---|---|
| Alternaria | Low | 13/100 |
| Cladosporium | Low | 21/100 |
Tomorrow - 11 October
| Mold species | Level | Value | 7-Day Trend |
|---|---|---|---|
| Alternaria | Low | 4/100 | Steady |
| Cladosporium | Low | 11/100 | Steady |
Local Mold Conditions
Organic material for mold is moderately available around this part of Philadelphia, mostly in the green spaces among the buildings. Among the buildings, gardens, parks and street trees supply compost, mulch and fallen leaves in smaller pockets. Compost bins, leaf piles and mulched borders near houses are further local sources.
Cladosporium, the most common outdoor mold, grows on compost, mulch and leaves from April to October, peaking in July when temperatures average about 26°C. Alternaria needs more warmth and is most abundant in July. Outdoor mold is largely dormant from December to February, when temperatures stay under 5°C. Daily levels tend to climb through dry, windy afternoons and drop during prolonged rain.
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Mold forecast neighborhoods 144 neighborhoods
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Frequently Asked Questions About Mold in Pennsylvania
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 mold scores represent risk levels, not direct mold measurements. Higher scores indicate higher risk.
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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