Portola Valley, CA Pollen Count Today

What is the Portola Valley pollen count today?

The Portola Valley pollen count today is 25 out of 100 (Low) on the Pollen Atlas Total Pollen Index, driven mainly by Ragweed.

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

Portola Valley allergies today

Portola Valley allergies today are set by the same reading as the pollen count above: the Total Pollen Index is 25 (Low), driven mainly by Ragweed. When people ask about Portola Valley allergies, this is the number that answers them — one daily index built from today’s tree, grass, weed and mold readings for Portola Valley.

Allergies in Portola Valley 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 Portola Valley 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 Portola Valley allergy forecast: today reads 25 (Low), and the day-by-day outlook shows whether Portola Valley 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 Portola Valley today records is this same combined reading — tree, grass, weed and mold in one index.

The Portola Valley allergy count today is 25 (Low) — the same Total Pollen Index as the pollen count above, in one combined reading.

Pollen count today Portola Valley: the 5-day forecast

Pollen Atlas forecasts Portola Valley’s pollen count to peak on Saturday at 25 (Low) over the next 5 days.

Pollen by type in Portola Valley

• Portola Valley tree pollen count
• Portola Valley grass pollen count
• Portola Valley ragweed pollen count

What is driving Portola Valley’s pollen today

The shape of today’s 25 (Low) is set by tree pollen at 29 (Low on its own scale) — about 52% of the four category readings added together, 4 points clear of the next category, weed pollen at 25. Tree readings are the fastest-moving of the four in their season, because species pollinate in sequence — a tree-led total can change character within a week. Tree pollen leading in November runs against the usual calendar — the California tree chapter runs February to May — 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 Portola Valley, 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 20 to 25, never changing band. Today’s 25 sits 2 points above the window’s average of 23.4 — a steady window, in which one day reads much like the next.

Plants affecting Portola Valley now

Detailed plant-by-plant readings for Portola Valley 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 29 (Low).

Grass pollen is one of the categories with a non-zero reading today, at 2 (Low).

Weed pollen is one of the categories with a non-zero reading today, at 25 (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.

Portola Valley pollen through the year

Three chapters make the California pollen year, and Portola Valley 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 Portola Valley 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 Portola Valley, 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.

Portola Valley in today’s national picture

At 25 (Low), Portola Valley ranks joint 33676th of the 90896 cities Pollen Atlas tracks today — in the middle of the national table. The highest reading in the country today is Beja, Portugal at 52, and the lowest is Los Ángeles de San Rafael, Spain at 5. The whole table spans 47 points today — a wide-open day, when the top and bottom of the table are effectively in different seasons.

Around Portola Valley: Ladera, CA (3 miles away) reads 25 (Low); La Honda, CA (4 miles away) reads 22 (Low); Woodside, CA (4 miles away) reads 25 (Low). Portola Valley 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 Portola Valley resident untouched and floor another, depending on which pollens they are sensitised to. If this pattern finds you every season, allergists in Portola Valley, 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.

Portola Valley in its local area

Across California’s 1602 tracked cities, Portola Valley ranks joint 366th today.

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

Nearby cities

• Ladera pollen count (3 miles away)
• La Honda pollen count (4 miles away)
• Woodside pollen count (4 miles away)
• West Menlo Park pollen count (5 miles away)
• Los Altos Hills pollen count (5 miles away)
• Palo Alto pollen count (5 miles away)

From Pollen Atlas News

• California allergy season
• Ragweed season