When Does Spring Allergy Season End? Tree and Grass Pollen

What drives spring allergy season?

Spring allergy season is caused by tree and grass pollen released as temperatures warm. Each plant species pollinates on its own schedule, which means spring season is really a sequence of overlapping pollen windows rather than a single event.

Temperature is the main trigger: a warm spell in February can bring tree pollination weeks earlier than usual, while a cold, wet spring delays it. Rainfall lowers pollen counts temporarily — but pollen bounces back after rain stops — and wind accelerates release and spread 1Ref 1Seidman MD, Gurgel RK, Lin SY, Schwartz SR, Baroody FM, Bonner JR, et al. (2015).Clinical Practice Guideline: Allergic Rhinitis.Seasonal allergic rhinitis; tree and grass pollen as major spring triggers; regional pollen season variation.

When is tree pollen season?

In most of the continental US, tree pollen season follows a rough regional timeline:

• Southeast and Gulf Coast: January–March (earliest; warmer winters mean earlier trees)
• Mid-Atlantic, Ohio Valley, Midwest: March–May
• Northeast and Upper Midwest: April–June
• Pacific Northwest: February–May for alder and birch; later for oak and ash
• Mountain West: Often shorter, typically April–June

The most allergenic trees vary by region but commonly include oak, birch, alder, cedar/juniper (which can pollinate in winter in some areas), maple, elm, ash, and sycamore. In many parts of the South, mountain cedar (actually a juniper) is the dominant December–February allergen.

Tree pollen season is typically the most intense spring season for people sensitive to these plants 1Ref 1Seidman MD, Gurgel RK, Lin SY, Schwartz SR, Baroody FM, Bonner JR, et al. (2015).Clinical Practice Guideline: Allergic Rhinitis.Seasonal allergic rhinitis; tree and grass pollen as major spring triggers; regional pollen season variation.

When is grass pollen season?

Grass pollen follows trees and overlaps with the tail of tree season:

• Southeast: April–June
• Most of US: May–July
• Southern California and Gulf Coast: Can extend almost year-round for some grasses

Common allergenic grasses include timothy, bluegrass, ryegrass, Bermuda, and Johnson grass. If your allergies feel like they linger into June and July after the spring trees are done, grass pollen is likely the culprit.

Tree and grass allergies can co-exist, meaning some people have symptoms from late February all the way through July with very little break 1Ref 1Seidman MD, Gurgel RK, Lin SY, Schwartz SR, Baroody FM, Bonner JR, et al. (2015).Clinical Practice Guideline: Allergic Rhinitis.Seasonal allergic rhinitis; tree and grass pollen as major spring triggers; regional pollen season variation.

When does spring allergy season end?

For most people in most US regions:

• Tree pollen ends by mid-to-late May in the Northeast and Midwest
• Grass pollen ends by mid-July in most of the US
• There is then a relatively quiet period in late July and early August before ragweed season begins in late August

For those allergic only to tree pollen, the season can feel over by June. For grass-sensitive individuals, relief may not arrive until mid-summer. And for those with allergies across all three seasons — tree, grass, and ragweed — meaningful relief may not come until October's first frost 1Ref 1Seidman MD, Gurgel RK, Lin SY, Schwartz SR, Baroody FM, Bonner JR, et al. (2015).Clinical Practice Guideline: Allergic Rhinitis.Seasonal allergic rhinitis; tree and grass pollen as major spring triggers; regional pollen season variation.

How can I track when pollen is high in my area?

Pollen counts are measured and reported daily by certified stations across the US and reported by category (tree, grass, weed). Many weather apps and sites like the National Allergy Bureau (pollen.com) publish regional pollen counts. Checking these on high-count days helps you:

• Decide whether to limit outdoor activity
• Know when to take a pre-activity antihistamine or nasal spray
• Anticipate when your season is winding down

Pollen counts are highest on warm, dry, windy mornings. Rain drops counts sharply — at least temporarily.

How do I manage symptoms through the whole spring season?

Start before the season. Beginning an intranasal corticosteroid spray one to two weeks before your typical symptom start date gives the anti-inflammatory effect time to develop before your immune system is challenged 2Ref 2Bousquet J, Schünemann HJ, Togias A, Bachert C, Erhola M, Hellings PW, et al. (2020).Next-generation Allergic Rhinitis and Its Impact on Asthma (ARIA) guidelines for allergic rhinitis based on Grading of Recommendations Assessment, Development and Evaluation (GRADE) and real-world evidence.Intranasal corticosteroid first-line therapy; pre-season start strategy; layered treatment approach.

Stay with it through the end. Stopping medication as soon as you feel better often leads to a symptom rebound, especially if pollen season is still ongoing.

Layer treatments for peak days. Intranasal corticosteroids work best for baseline control. Adding a non-sedating antihistamine or antihistamine eye drops on high-pollen days gives extra coverage.

Consider immunotherapy for lasting change. If multiple seasons or several years of allergy are disrupting your life, allergen immunotherapy can reduce long-term sensitivity and is worth a conversation with an allergist 3Ref 3Gurgel RK, Baroody FM, Damask CC, Mims JW, Ishman SL, Baker DP Jr, et al. (2024).Clinical Practice Guideline: Immunotherapy for Inhalant Allergy.Immunotherapy for lasting reduction in pollen allergy sensitivity.

A Gale primary care clinician can help build a season-long medication plan and refer you to an allergist if that becomes appropriate.