Half Moon Bay, California Pollen Count

Half Moon Bay pollen count and allergy forecast — tree, grass, and ragweed seasons and what’s pollinating now

Half Moon Bay, CA · Pollen count right now

Grass pollen is Very Low in Half Moon Bay today

Grass: Very Low 1/5Tomorrow: Low

Today’s pollen by type

Active now: Pine, Oak, Grasses.

Half Moon Bay pollen calendar

Typical peak months for each pollen type in this climate region. The highlighted column is the current month.

JFMAMJJASOND
TreeJan–Apr
GrassMar–Jun
WeedAug–Oct

How Half Moon Bay’s pollen count works

Pollen rises in three overlapping waves through the year: trees release first, in late winter and spring; grasses peak from late spring into summer; and weeds — ragweed above all — take over from late summer into fall. The calendar above shows the typical peak window for each in Half Moon Bay’s climate region, so you can see what’s likely driving your symptoms before you ever check a number.

Counts are reported on a categorical scale — None, Low, Moderate, High, and Very High. Levels run highest on warm, dry, windy mornings and fall after rain, which washes pollen out of the air. If a live count is available it appears at the top of this page; otherwise the seasonal calendar is your guide to when each allergen is in season in Half Moon Bay.

Frequently asked

When is pollen worst in Half Moon Bay?
Half Moon Bay's pollen season runs in three overlapping waves: tree pollen peaks Jan–Apr, grass pollen Mar–Jun, and weed (ragweed) pollen Aug–Oct. The single worst stretch for most people is the spring tree peak and the late-summer ragweed peak; the live count at the top of this page tells you which is active today.
What's pollinating in Half Moon Bay right now?
In June, grass pollen is in season in Half Moon Bay — the dominant allergen you're likely reacting to right now. The live index above (when available) confirms the day's actual count; this calendar reflects the typical peak windows for Half Moon Bay's climate region.
Is tree or grass pollen higher in Half Moon Bay in spring?
In spring, tree pollen usually dominates in Half Moon Bay — trees pollinate Jan–Apr, ahead of the grass peak (Mar–Jun). Late spring is the handoff: tree counts taper as grass climbs, so a bad April is more likely tree pollen and a bad late-May/June is more likely grass.
How do I reduce pollen exposure in Half Moon Bay?
Keep windows closed and run air conditioning on recirculate during peak season; counts are highest on dry, warm, windy mornings, so time outdoor activity for late afternoon or after rain, which washes pollen out of the air. A HEPA air purifier indoors, a saline nasal rinse after being outside, showering and changing clothes before bed, and starting antihistamines before your worst season begins all measurably cut symptoms.
What pollen index counts as high?
Pollen is reported on a categorical scale — None, Low, Moderate, High, and Very High. "High" and above means most allergy sufferers will notice symptoms even with brief outdoor exposure, and sensitized people should limit time outside and pre-medicate. "Low" to "Moderate" usually only affects highly sensitive individuals.

More for Half Moon Bay

See the full Half Moon Bay, CA weather forecast — hour-by-hour outlook, NOAA radar, satellite, and air quality.

Pollen counts nearby in California