St. Catharines, ON Pollen Count
St. Catharines, ON · Last updated Friday, November 6, 2026
This page shows the most recent reading available for St. Catharines — from Friday, November 6, 2026 (1 day ago) — not today's reading.
Pollen Overview
Today's overall pollen level and the dominant type (trees, weeds, grass, or mold).
Total Pollen Index
The combined pollen level across all types (0–100).
St. Catharines, ON
Weeds Index
How active weeds pollen is today (0–100).
St. Catharines, ON
Pollen Types
Pick a pollen subtype to update the species forecast
5-Day St. Catharines Overall Pollen Forecast
Bars are colored by severity (Low/Moderate/High).
Pollen count St. Catharines residents check each morning
The St. Catharines pollen count today is 22 (Low). The main driver is Ragweed, with weed pollen at 29 today. Weed pollen leads the split at 29 (Low on its own scale), followed by grass pollen at 1 and tree pollen at 0.6. Below, the plant detail and the multi-day outlook show whether today is the pattern or the exception. Pollen Atlas updated this count on Friday, November 6, 2026.
A Low band on the Pollen Atlas index means the Total Pollen Index has stayed in the lower part of the 0–100 scale. Readings in this band are built from low individual category values rather than from one large spike, and the category split above matters more than the headline number: a low total can still contain one category, such as weed pollen or mold, reading noticeably higher than the rest, which is why the split is printed on every St. Catharines page.
Fall is ragweed season across most of North America: ragweed plants release pollen from late summer into autumn, and weed pollen is typically the last major outdoor pollen category to fade as the weather cools. That pattern is why an autumn total is so often weed-led even when the headline number is low — tree and grass pollen have usually receded by then, leaving weed pollen, and on damp days mold, to make up most of what the index records. In the Plains and around the Great Lakes, ragweed is a familiar late-season plant of open ground, field edges and disturbed soil, which is why it so often leads inland autumn readings.
To see whether today’s pollen level holds, check the 5-day St. Catharines pollen forecast below — it is currently holding, with Friday the highest day in the window.
This is the pollen count St. Catharines residents check each morning, built from the day’s tree, grass, weed and mold readings.
What is the St. Catharines pollen count today?
The St. Catharines pollen count today is 22 out of 100 (Low) on the Pollen Atlas Total Pollen Index, driven mainly by Ragweed.
Short answer for anyone searching pollen count today St. Catharines: this page is updated every morning with the day’s modelled reading.
St. Catharines allergies today
St. Catharines allergies today are set by the same reading as the pollen count above: the Total Pollen Index is 22 (Low), driven mainly by Ragweed. When people ask about St. Catharines allergies, this is the number that answers them — one daily index built from today’s tree, grass, weed and mold readings for St. Catharines.
Allergies in St. Catharines follow the Ontario 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. Catharines 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. Catharines allergy forecast: today reads 22 (Low), and the day-by-day outlook shows whether St. Catharines 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. Catharines today records is this same combined reading — tree, grass, weed and mold in one index.
The St. Catharines allergy count today is 22 (Low) — the same Total Pollen Index as the pollen count above, in one combined reading.
Pollen count today St. Catharines: the 5-day forecast
| Day | Total Pollen Index | Band |
|---|---|---|
| Friday, November 6 | 22 | Low |
| Saturday, November 7 | 22 | Low |
| Sunday, November 8 | 22 | Low |
| Monday, November 9 | 21 | Low |
| Tuesday, November 10 | 18 | Low |
Pollen Atlas forecasts St. Catharines’s pollen count to peak on Friday at 22 (Low) over the next 5 days.
Pollen by type in St. Catharines
What is driving St. Catharines’s pollen today
The shape of today’s 22 (Low) is set by weed pollen at 29 (Low on its own scale) — about 95% of the four category readings added together, 28 points clear of the next category, grass pollen at 1. 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 Ontario 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. Catharines, so the drivers have to be read from the category split above — it shows how much of today’s total each category is actually carrying, and plant detail returns here automatically on any day the feed includes it.
Across the five-day window the Total Pollen Index runs from 18 to 22, never changing band. Today’s 22 sits 1 point above the window’s average of 21 — a steady window, in which one day reads much like the next.
Plants affecting St. Catharines now
Detailed plant-by-plant readings for St. Catharines 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 0.6 (Low).
Grass pollen is one of the categories with a non-zero reading today, at 1 (Low).
Weed pollen is one of the categories with a non-zero reading today, at 29 (Low).
In the Midwest & Great Lakes pattern, the plants that typically shape this city’s year are spring trees, late-spring and summer grasses, and late-summer and autumn ragweed — 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. Catharines pollen through the year
Three chapters make the Ontario pollen year, and St. Catharines follows them in the Midwest & Great Lakes order. The tree chapter: trees run from March into May, later near the big lakes. The grass chapter: grasses hold from May through July. The weed chapter: ragweed builds from mid-August, peaks in September, and ends at the first frost. Mold builds through the humid summer and fills the gaps between chapters.
No Ontario allergy season guide is published yet, so this page does not single out signature pollens for St. Catharines — the calendar above is the Midwest & Great Lakes regional pattern, and the plant detail on this page names what today’s feed actually records.
November falls between the main chapters of the Ontario 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 8 months of the Ontario year, March to October — a compressed season, which is why its chapters arrive in quick succession. No Ontario allergy season guide is published yet — this calendar follows the Midwest & Great Lakes regional pattern. See St. Catharines pollen count rankings and St. Catharines on the pollen heatmap.
How to read this index
Pollen Atlas reports the St. Catharines 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. Catharines, ON 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. Catharines in today’s US & Canada picture
At 22 (Low), St. Catharines ranks joint 44134th of the 90896 cities Pollen Atlas tracks today — in the middle of the combined US & Canada table. The highest reading on the combined table 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. Catharines: Niagara Falls, ON (9 miles away) reads 15 (Low); Lewiston, NY (10 miles away) reads 20 (Low); Niagara University, NY (11 miles away) reads 16 (Low). St. Catharines reads 7 points higher than its nearest tracked neighbour today. Across Ontario’s 41 tracked cities, today runs from 5 in Ottawa to 34 in Ajax.
Pollen totals are population numbers; symptoms are personal. The same reading can leave one St. Catharines resident untouched and floor another, depending on which pollens they are sensitised to. If this pattern finds you every season, allergists in St. Catharines, ON 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. Catharines in its local area
St. Catharines is in Regional Municipality of Niagara, Ontario, Canada. Its population is 136,803 (GeoNames).
Across Ontario’s 41 tracked cities, St. Catharines ranks joint 16th today.
Like every Pollen Atlas city page, the St. Catharines, ON pollen count is refreshed each morning.
Nearby cities
- Niagara Falls pollen count (9 miles away)
- Welland pollen count (12 miles away)
- Oakville pollen count (31 miles away)
- Burlington pollen count (31 miles away)
- Hamilton pollen count (32 miles away)
- Mississauga pollen count (36 miles away)
From Pollen Atlas News
See how St. Catharines ranks in today's pollen count rankings — the worst cities for allergies today
Pollen indexes: a modelled pollen risk index computed by Pollen Atlas from open weather, vegetation and phenology data, calibrated against CDC/NAB season data. Plant detail: Google Pollen API. Index values are modelled, not measured counts. Sources: CDC/NAB; USA-NPN; GBIF (CC BY); ESA WorldCover (CC BY 4.0).