Los Angeles Mold Forecast
Mold Today
Today (16 September) mold in Los Angeles is moderate; cladosporium is moderate; alternaria is low.
Mold Tomorrow
Tomorrow (17 September 2026) alternaria remains low, cladosporium declining.
7-Day Trend
Over the next week alternaria and cladosporium will decrease.
Explore Forecasts
Pollen & Air Quality
Mold in Other Cities
Routes
Get More in Our App
Local pollen and air quality forecasts, interactive pollen maps and route profiles
Features and forecast availability vary by region.
Mold Risk
Today - 16 September
| Mold species | Level | Value |
|---|---|---|
| Alternaria | Low | 18/100 |
| Cladosporium | Moderate | 29/100 |
Tomorrow - 17 September
| Mold species | Level | Value | 7-Day Trend |
|---|---|---|---|
| Alternaria | Low | 18/100 | Steady |
| Cladosporium | Low | 25/100 | Steady |
Local Mold Conditions
In Los Angeles, soil moisture averages 41.2%, and a temperate climate means there is a distinct period each year when temperature and moisture both favour mold. Organic material for mold is present, though not exceptional. Both species are constrained — Cladosporium by low moisture, Alternaria by a combination of dryness and temperature.
Los Angeles has a distinct mold season tied to when temperature and moisture are both high enough to support growth simultaneously. Soil moisture reaches 53.1% in December and drops to its lowest in June. Where that wet period overlaps with warmer temperatures, mold conditions are most favourable. 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.
Get pollen & AQ on Strava
Follow your environmental exposure and performance with the free Airmine-Strava integration. See your pollen and air quality exposure for every Strava activity.
Resource Hub
Pollen forecast neighborhoods 383 neighborhoods
Sports venues in Los Angeles 5 sports venues
Popular Local Routes 13 routes
Local events 1 event
Frequently Asked Questions About Mold in California
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. |
Get More in the Airmine Pollen app
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.
Developed with support from the European Space Agency (ESA) Business Applications and Space Solutions (BASS).
