June Allergies: The Month Grass Pollen Takes Over
By the time June allergies arrive, many people assume pollen season is winding down — the trees are leafed out, the spring dust is gone, and summer has begun. In most of the United States, June allergies tell a different story: June is grass pollen's peak month, the main act of a season that trees merely opened. Lawns, meadows, pastures, and roadsides flower together, and the Grass Index, not the Tree Index, becomes the number that decides the day.
Key takeaways
- June is the peak grass month across most of the northern and central US: the ACAAI pollen overview places grass pollen's main season in late spring and summer, after the tree peak.
- Pollen Atlas data shows the June Grass Index in cities such as Minneapolis and New York regularly exceeding their spring Tree Index peaks — June is not a tail of the season but its centre for grass-sensitive readers.
- The handoff is regional: the CDC's allergens overview notes pollen type follows season and geography, and southern grasses peak earlier, in May, while northern grasses peak in June and into July.
- Pollen Atlas data shows June counts swinging sharply with mowing and weather — a dry, breezy week after rain-driven growth produces the month's highest grass days.
What is still pollinating when June allergies hit
The June cast is grass-led. Cool-season grasses — bluegrass, ryegrass, timothy, orchard grass, and fescues — flower across the North and the transition zone, while Bermuda grass builds through the South. Weed pollens are mostly still minor in June, with plantain and dock among the early contributors, and a few late trees finish in northern states in the month's first weeks. The grass pollen season guide profiles the main grass species and their overlapping windows.
That grass dominance changes the texture of the season. Tree pollen season is a canopy event, strongest near flowering trees and largely finished once each species flowers. Grass season is a ground-level event renewed daily: unmown fields keep releasing, mowing itself throws pollen and fragments into the air, and new growth after rain flowers again. June's pollen is therefore both steadier and more weather-sensitive than April's.
The handoff from trees to grasses
In most northern cities the handoff happens across late May: tree indexes fall as the last oaks finish, grass indexes climb as lawns and meadows come into flower, and for a week or two both read moderate at once. Readers who feel worse in that overlap week than in either peak are meeting the combined load. The pollen season calendar shows the handoff month by month for the whole country.
Why June allergies peak in the North and ease in the South
Grass flowering follows temperature and day length, and the South gets there first. Southern grasses — Bermuda above all — begin in spring and can peak in May, then continue at moderate levels through summer, throttled by heat. Northern grasses wait for sustained warmth and flower in a concentrated burst: in Minneapolis, Minnesota, June is reliably the grass peak, and in New York, New York the same pattern holds, with city parks, suburbs, and upwind meadows all contributing. At elevation, Denver, Colorado runs its grass peak later still, often from June into July, on irrigated turf and foothill grasses.
| Region | Grass peak timing | June character |
|---|---|---|
| South and Gulf Coast | May peak, long tail | June is moderate and heat-throttled; Bermuda leads |
| Mid-Atlantic and Midwest | Late May into June | June is the heart of grass season |
| Northern states and New England | June into early July | June is the peak month |
| Mountain West | June into July | Later, irrigation-shaped, sharp dry-day spikes |
Rain grows it, dry wind spreads it
June weather writes the daily story everywhere. Rain in late May grows lush grass; a following dry, breezy week flowers it and spreads the pollen widely — the classic recipe for the month's worst stretch. Rain during June itself washes counts down briefly, then regrowth refills them. This grow-and-release rhythm is why June indexes oscillate more than spring tree indexes, and why a five-day outlook is especially useful in this month.
June allergies and the almost-summer traps
June concentrates outdoor exposure: school ends, sports move outside, mowing peaks, and hay is cut in farm country. Haymaking deserves a mention — cutting and baling grass at flowering throws large quantities of pollen and plant material into local air, and rural counts can spike around it. Outdoor mold also builds through June as soils warm and vegetation thickens, so the month's air increasingly mixes grass pollen with rising spore levels, a combination the AAFA Allergy Capitals research reflects in the weight it gives grass scores for northern cities.
What a June count is really telling you
A high June Grass Index usually means a regional event, not a single lawn: when weather aligns, every unmown surface in a metro flowers together. That is why June highs can feel inescapable compared with tree season, when moving a few streets from a flowering oak could change your day. The national city rankings in June typically show a northern and central sweep — whole regions in the high band at once.
Reading June in the daily indexes
On Pollen Atlas, June is the month to watch the Grass Index first and the Tree Index second — the reverse of April. City pages score both from 0 to 100 with per-plant detail, so you can see whether ryegrass, bluegrass, or Bermuda is leading your local reading, and the five-day outlook captures the grow-and-release swings grass season is known for.
If June is reliably your hardest month and you want to know which grass is responsible, the Pollen Atlas Find an Allergist directory lists specialists by location. This article is general information about a seasonal pattern, not medical advice.
The June rule of thumb
If the trees have finished and symptoms have not, it is grass. Expect the North's peak, the South's long tail, and the sharpest days after rain-fed growth meets a dry, breezy week.
Frequently Asked Questions
What pollen is high in June?
Grass pollen is high in June across most of the United States — bluegrass, ryegrass, timothy, and orchard grass in the North and Bermuda grass in the South — while most tree pollen has finished.
Why are my allergies worse in June than in spring?
June can feel worse because grass pollen peaks then in northern and central states, and the combined load of the tree-to-grass handoff, mowing, and rising outdoor mold adds to the grass peak.
When does June grass pollen end?
Northern grass pollen typically eases during July as flowering finishes and heat or drought sets in, while southern Bermuda grass continues at moderate levels through much of the summer.
Is June too late for tree pollen?
Mostly, in the South and mid-Atlantic, where trees finish by May — but northern and high-elevation trees can still contribute in early June before grasses fully take over.
Sources
American College of Allergy, Asthma & Immunology pollen overview (accessed 2026); Centers for Disease Control and Prevention, Allergens and Pollen (accessed 2026); Asthma and Allergy Foundation of America, Allergy Capitals reports (2025–2026).
Conclusion
June allergies are the season's second act, and for much of the country they are the main one. Trees open the year, but grasses own June: a ground-level, weather-driven, regionally synchronised peak that runs from the northern states' sharp burst to the South's long Bermuda tail. Read the Grass Index first this month, respect the dry and breezy days after rain, and June allergies become a forecast you can plan around rather than a surprise hiding behind the assumption that pollen season ended in spring.
Check the pollen before it checks you — free counts and forecasts, worldwide: PollenAtlas.com