Phoenix Mold Forecast
Mold Today
Today (16 September) mold in Phoenix is low; alternaria and cladosporium are low.
Mold Tomorrow
Tomorrow (17 September 2026) levels are similar to today.
7-Day Trend
Over the next week alternaria and cladosporium will decrease.
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Mold Risk
Today - 16 September
| Mold species | Level | Value |
|---|---|---|
| Alternaria | Low | 15/100 |
| Cladosporium | Low | 19/100 |
Tomorrow - 17 September
| Mold species | Level | Value | 7-Day Trend |
|---|---|---|---|
| Alternaria | Low | 18/100 | Steady |
| Cladosporium | Low | 23/100 | Steady |
Local Mold Conditions
In Phoenix, soil moisture averages 18.8%, and a temperate climate means there is a distinct period each year when temperature and moisture both favour mold. Organic matter for mold to feed on is typically limited. Conditions are poor for both species: low moisture constrains Cladosporium, while Alternaria is further limited by temperature.
Mold's season in Phoenix is shaped by the overlap of warm temperatures and adequate moisture — and those two don't always peak together. Moisture peaks at 21.8% in December; the driest point is April. The best mold conditions tend to occur where this moisture peak overlaps with the warmer season. As dry-spored fungi, both species release spores in dry, breezy weather — meaning airborne counts lag behind the growth peak and rise as conditions dry.
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Resource Hub
Pollen forecast neighborhoods 11 neighborhoods
Sports venues in Phoenix 1 sports venue
Popular Local Routes 12 routes
Frequently Asked Questions About Mold in Arizona
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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