Is This Allergy Season? How to Tell, Month by Month
The question "is this allergy season" sounds simple, and in the United States it almost never has a single answer. On any given date, several regional seasons are running at once: Florida can be in tree season while the upper Midwest is still dormant, and the Southwest can be starting while the Northeast is finishing. So is this allergy season where you are? The reliable way to answer is to match three things — the month, your region, and which pollen family is in its window — because the American "season" is really a relay of tree, grass, and weed seasons moving across the map on different dates.
Key takeaways
- The National Allergy Bureau's station network shows U.S. regions entering and leaving pollen seasons weeks apart on the same dates.
- Tree pollen opens the year — as early as January in the Deep South and Florida, and as late as April in the far North, per NAB reporting patterns.
- Pollen Atlas data shows at least some U.S. cities recording elevated readings in every month of a typical year.
- Grass season bridges spring and summer, and ragweed season runs from August to first frost, per AAFA seasonal resources.
- The fastest local answer is a count, not a calendar: the day's index for your city states whether your season is active now.
The relay: three seasons, not one
The continental pattern is a relay. Trees go first, in a wave that moves north with spring warming. Grasses take the baton in late spring and hold it through early summer — longer in the South. Weeds, above all ragweed, run the final leg from August to frost. In the warmest regions the legs overlap so much that the relay looks continuous; in the coldest, there are real gaps of quiet between them.
Winter: the season that already started somewhere
In January and February, most of the country answers "no" — but the Gulf Coast, Florida, and parts of Texas and the Southwest are already recording tree pollen. Atlanta pollen counts typically show the Southeast's tree season opening weeks before the Northeast's, and Dallas pollen counts can register cedar-family pollen in the heart of winter. The month-by-month national picture is laid out in the pollen season calendar.
Spring: the whole map lights up
March through May is the one window when the answer is "yes" nearly everywhere. Tree pollen peaks region by region — earlier in the South, later in the North — and grass joins from April onward. The spring allergy season guide covers this peak in depth. Pollen Atlas data shows spring producing the highest single-day tree readings of the year in most cities, even in places whose total annual burden is modest.
Is this allergy season in summer and fall? The regional split widens
By July, the map fragments. Northern cities often get a genuine mid-summer lull after grass fades; southern cities run grass and early weeds with barely a pause; the desert Southwest follows its own monsoon-influenced rhythm, visible in Phoenix pollen counts.
August to frost: weed season
From August, ragweed unifies the map again — most of the country east of the Rockies is in weed season until frost ends it, north first and south last. The pollen heatmap shows the season's edge moving south week by week each autumn, which is the relay's final leg drawn as data. The AAAAI's seasonal resources at aaaai.org describe the same structure.
| Month range | South / Gulf | Midwest / Plains | Northeast | West / Southwest |
|---|---|---|---|---|
| Jan–Feb | Tree season opening | Mostly dormant | Dormant | Cedar-type pollen in the Southwest |
| Mar–May | Tree peak, grass starts | Tree, then grass | Tree, then grass | Tree, then grass |
| Jun–Jul | Long grass, mold | Grass, summer lull late | Grass, July lull | Grass varies; desert patterns differ |
| Aug–Oct | Ragweed + mold to late frost | Ragweed peak September | Ragweed to October frost | Ragweed lighter; local weeds |
Is this allergy season for your city today?
The calendar narrows the answer; the count settles it. If today's index for your city shows the tree, grass, or weed component elevated, your season — whichever leg of the relay you are on — is active, regardless of what the month usually means. The Asthma and Allergy Foundation of America frames its seasonal guidance the same way: regional calendars for context, local counts for decisions about the day. National Allergy Bureau stations publish through pollen.aaaai.org for readers who want the underlying station record.
Readers researching providers in their area can use the Find an Allergist directory, searchable by city and distance, as a general reference alongside the count data.
A few edge cases round out the national picture. Hawaii and tropical territories run flowering calendars with no winter pause at all, governed more by rainfall than temperature. Alaska's season is the nation's most compressed, a brief, intense summer window. Mountain communities can be in tree season weeks after their nearest city, at the same latitude, because elevation delays spring. And the Pacific Coast splits by rain shadow: coastal ranges green and flower on one schedule while the interior valleys behind them run earlier and drier. None of these change the relay model — they extend it. Each is still a local sequence of tree, grass, and weed windows, still bounded by frost or dry season, still readable in a daily count. That is ultimately why the question survives every calendar anyone publishes: the United States is too climatically varied for one season, so the honest answer is always a local answer, and local answers are exactly what count data exists to provide.
One practical habit follows from all of this: check the components, not just the headline number. A moderate total can hide a high weed component in September or a high tree component in April, and the component is what tells you which season you are actually standing in on that particular day.
Frequently Asked Questions
Is this allergy season right now in the United States?
Somewhere in the U.S., yes, in almost every month: Pollen Atlas data shows elevated readings in at least some cities year-round. Whether it is the season in your city depends on your region's calendar and today's count.
What months are allergy season in most states?
Most states run tree season in spring (roughly March–May, earlier in the South), grass season in late spring and early summer, and weed season from August to first frost, per AAFA and National Allergy Bureau seasonal patterns.
Why does allergy season start earlier in the South?
Warmer winter and spring temperatures trigger earlier tree flowering in southern states, and the frost-free season is longer, so southern calendars start weeks ahead of northern ones and end later, per NAB station reporting.
How can I tell which pollen season my region is in?
Match the month to the relay — trees in spring, grasses in late spring and summer, weeds from August — then confirm with your city's daily component readings, which show which family is elevated on a given day.
Conclusion
So, is this allergy season? Nationally, the relay never fully stops; locally, the answer is written in your region's calendar and confirmed by today's count. Learning which leg of the relay your city is on turns a guessing question into a thirty-second check. Free counts. Free forecasts. Worldwide. PollenAtlas.com has your day covered.
Sources
- American Academy of Allergy, Asthma & Immunology (AAAAI) / National Allergy Bureau, seasonal station reporting (2025).
- Asthma and Allergy Foundation of America (AAFA), seasonal allergy resources and Allergy Capitals report (2024–2025).
- Pollen Atlas monthly city count data (2026).