St. Helena, CA Pollen Count

What is the St. Helena pollen count today?

The St. Helena pollen count today is 18 out of 100 (Low) on the Pollen Atlas Total Pollen Index, driven mainly by Ragweed.

Short answer for anyone searching pollen count today St. Helena: this page is updated every morning with the day’s modelled reading.

St. Helena allergies today

St. Helena allergies today are set by the same reading as the pollen count above: the Total Pollen Index is 18 (Low), driven mainly by Ragweed. When people ask about St. Helena allergies, this is the number that answers them — one daily index built from today’s tree, grass, weed and mold readings for St. Helena.

Allergies in St. Helena follow the California calendar set out below — the chapters, the plants behind them, and the 5-day forecast on this page show whether today is typical for the season or an exception to it. If you are checking allergies today in St. Helena before heading outdoors, the split at the top of this page is the part to read: it shows which pollen is doing the work today, not just how high the total sits.

Read the five-day table on this page as the St. Helena allergy forecast: today reads 18 (Low), and the day-by-day outlook shows whether St. Helena allergies are set to ease or build across the week — the days to plan outdoor time around are the ones where the index steps down, not just today.

In practice, the allergy count St. Helena today records is this same combined reading — tree, grass, weed and mold in one index.

The St. Helena allergy count today is 18 (Low) — the same Total Pollen Index as the pollen count above, in one combined reading.

Pollen count today St. Helena: the 5-day forecast

Pollen Atlas forecasts St. Helena’s pollen count to peak on Friday at 18 (Low) over the next 5 days.

Pollen by type in St. Helena

• St. Helena tree pollen count
• St. Helena grass pollen count
• St. Helena ragweed pollen count

What is driving St. Helena’s pollen today

The shape of today’s 18 (Low) is set by weed pollen at 21 (Low on its own scale) — about 52% of the four category readings added together, 2 points clear of the next category, tree pollen at 19. A weed-led total is the classic late-year shape: tree and grass pollen have usually receded, leaving weed pollen — and on damp days mold — to make up most of what the index records. Weed pollen leading in November runs against the usual calendar — the California weed chapter runs August to October — so today’s lead is the model outranking the pattern, and this page reports the modelled reading first.

Plant-level detail is not in today’s feed for St. Helena, so the drivers have to be read from the category split above. The California guide’s account of California names planted olive and the Central Valley’s concentrated spring pollen — the pollens behind readings of this shape in this state — and the split shows how much of today’s total each category is actually carrying.

Across the five-day window the Total Pollen Index runs from 17 to 18, never changing band. Today’s 18 sits 0 points above the window’s average of 17.8 — a steady window, in which one day reads much like the next.

Plants affecting St. Helena now

Detailed plant-by-plant readings for St. Helena were not returned in today\u2019s source data, so this section summarises the pollen types the index above is built from instead of listing individual plants.

Tree pollen is one of the categories with a non-zero reading today, at 19 (Low).

Grass pollen is one of the categories with a non-zero reading today, at 0.6 (Low).

Weed pollen is one of the categories with a non-zero reading today, at 21 (Low).

In the California pattern, the plants that typically shape this city’s year are winter and spring trees, late-spring grasses and late-summer weeds — named here as regional context only, not as today\u2019s measurements.

Plant detail returns here automatically on any day the source data includes it.

Every pollen type, with photos and seasons: the pollen directory.

St. Helena pollen through the year

Three chapters make the California pollen year, and St. Helena follows them in the state’s own order. The tree chapter: trees build through spring, with planted olive peaking from March into May. The grass chapter: grasses peak in spring in the Central Valley and run longer and milder on the coast. The weed chapter: weeds follow in late summer and fall, stronger after wet winters.

There is no single California season: the Central Valley records some of the state’s sharpest spring peaks, trapped and concentrated by valley geography, while the coast runs long and mild. The AAFA’s 2025 Allergy Capitals research noted upward movement for several California cities, attributed to grass and weed pollen after wet weather. The California guide singles out planted olive and the Central Valley’s concentrated spring pollen.

November falls between the main chapters of the California pollen year — the tail of one and the approach of the next — so the calendar alone explains little today, and the modelled split above carries the story. Between them, the three chapters cover 9 months of the California year, February to October — leaving a quiet gap of roughly 3 months in the depth of the off-season. The full calendar is set out in the California allergy season guide.

How to read this index

Pollen Atlas reports the St. Helena pollen count on a Total Pollen Index from 0 to 100, built from separate tree, grass and weed readings. The total is a summary, not an average of the three: a single strong category can lift it, and three quiet categories can hold it down even in a month when St. Helena, CA pollen is usually more active. Index values are a modelled pollen risk index computed by Pollen Atlas from open weather, vegetation and phenology data, calibrated against CDC/NAB season data, with plant detail by the Google Pollen API. The index is a modelled 0–100 scale, not a measured count, and figures update through the day, so a morning and an evening visit to this page can legitimately show different numbers.

St. Helena in today’s national picture

At 18 (Low), St. Helena ranks joint 56739th of the 90896 cities Pollen Atlas tracks today — in the middle of the national table. The highest reading in the country today is Serpa, Portugal at 53, and the lowest is Galiakberovo, Russia at 5. The whole table spans 48 points today — a wide-open day, when the top and bottom of the table are effectively in different seasons.

Around St. Helena: Deer Park, CA (2 miles away) reads 18 (Low); Rutherford, CA (4 miles away) reads 25 (Low); Angwin, CA (5 miles away) reads 17 (Low). St. Helena reads exactly level with its nearest tracked neighbour today. Across California’s 1602 tracked cities, today runs from 5 in Truckee to 42 in Mecca.

Pollen totals are population numbers; symptoms are personal. The same reading can leave one St. Helena resident untouched and floor another, depending on which pollens they are sensitised to. If this pattern finds you every season, allergists in St. Helena, CA can test whether tree, grass, weed or mold is the category that matters for you — the four readings at the top of this page are the starting point for that conversation.

St. Helena in its local area

Across California’s 1602 tracked cities, St. Helena ranks joint 1128th today.

Like every Pollen Atlas city page, the St. Helena, CA pollen count is refreshed each morning.

Nearby cities

• Deer Park pollen count (2 miles away)
• Rutherford pollen count (4 miles away)
• Angwin pollen count (5 miles away)
• Oakville pollen count (6 miles away)
• Kenwood pollen count (8 miles away)
• Calistoga pollen count (8 miles away)

From Pollen Atlas News

• California allergy season
• Ragweed season