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Real-time pollen data for Philadelphia — updated daily. Powered by board-certified allergists.
Tree pollen drives Philadelphia's first allergy wave each spring. Oak is the dominant tree allergen in the greater Philadelphia region, with heavy pollen production from April through May. Hickory, maple, birch, ash, walnut, and willow trees are all significant contributors. Elm and cedar can begin releasing pollen as early as February during mild winters. The Delaware Valley's dense tree canopy — from Fairmount Park's 2,000+ acres to the tree-lined streets of Chestnut Hill, Germantown, and the Main Line suburbs — produces substantial pollen loads that blanket the metro area.
What makes Philadelphia different: The city sits in the Mid-Atlantic Coastal allergy region, where the convergence of warm, humid air from the south with cooler northern air masses can trap pollen at low altitudes for extended periods, prolonging high-count days.
Grass pollen overlaps with late tree pollen in May, creating a difficult transition period. Timothy grass, Kentucky bluegrass, ryegrass, Bermuda grass, fescue, bent grass, brome, and orchardgrass are the primary grass allergens in the Philadelphia area. The city's parks — Fairmount Park, FDR Park, Pennypack Park — and the expansive suburban lawns across Delaware, Montgomery, Chester, and Bucks counties are major pollen sources. Grass pollen peaks in June and can remain elevated through mid-July.
Philadelphia's position between the Schuylkill and Delaware Rivers creates microclimates with elevated humidity that can make grass pollen stickier and more irritating to sensitive airways.
Ragweed is Philadelphia's most potent fall allergen and one of the worst in the Mid-Atlantic region. The Asthma Center — Philadelphia's official pollen monitoring source since 1990 — consistently records ragweed as the dominant fall allergen, with counts peaking in September. Mugwort, pigweed, lamb's quarters, amaranth, and wormwood are additional weed triggers found in vacant lots, railroad corridors, and along the Schuylkill River Trail throughout the city.
Climate change has been extending Philadelphia's ragweed season, with warmer falls delaying the first hard frost — historically arriving in late October — that ends the outdoor pollen season.
Philadelphia's indoor allergen profile reflects its older urban housing stock. Dust mites thrive in the city's rowhomes, many built in the late 19th and early 20th centuries with limited ventilation and aging HVAC systems. Mold is a persistent issue in basements and bathrooms, particularly in rowhomes without modern moisture barriers. Cockroach allergens contribute to allergic asthma in multi-unit housing, and mouse allergens are also documented in older Philadelphia neighborhoods. Pet dander from cats and dogs adds to the year-round indoor allergen load.
During Philadelphia's cold winters (December through February), sealed windows and forced-air heating concentrate these allergens, often causing or worsening symptoms that residents may not associate with indoor triggers.
Philadelphia's cold winters provide genuine outdoor pollen relief, but indoor allergens intensify as residents seal up rowhomes and apartments and run heating systems. Dust mites, mold, pet dander, and mouse allergens concentrate in older housing. By late February, depending on winter severity, elm and cedar trees may begin releasing early pollen — Philadelphia's allergy season can start as early as February during mild winters.
Top allergens: Dust mites, indoor mold, pet dander, mouse allergens
Severity: Minimal (outdoor), moderate (indoor)
Tip: Change furnace filters monthly during heating season. If your rowhome has a damp basement, run a dehumidifier to keep humidity below 50% even in winter.
This is Philadelphia's most intense allergy period. Oak, birch, maple, hickory, ash, and walnut trees produce massive pollen loads across the Delaware Valley. April and May typically see the highest counts, with the overlap of late tree pollen and early grass pollen in May creating a brutal double exposure. Fairmount Park, Wissahickon Valley, and the tree-lined neighborhoods of Northwest Philadelphia and the Main Line become concentrated allergen sources.
Top allergens: Oak, birch, maple, hickory, ash, early grass
Severity: High to very high
Tip: The Asthma Center has provided daily pollen counts for the Philly region since 1990 — check their AI-powered pollen sensor data before planning outdoor time. Start allergy medications by early March, before tree pollen ramps up.
Grass pollen peaks in June as Timothy grass, bluegrass, and fescue dominate. By mid-July, grass pollen begins declining, but Philadelphia's notorious summer humidity drives mold spore counts to their annual highs. Warm, humid conditions from June through August create ideal mold growth environments both indoors and outdoors. Summer thunderstorms temporarily wash pollen from the air but trigger mold surges within 24–48 hours.
Top allergens: Timothy grass, bluegrass, fescue, mold spores (Alternaria, Cladosporium)
Severity: Moderate to high
Tip: Philadelphia's summer humidity makes AC essential for allergy management — not just for comfort but to control indoor mold and dust mites. Clean or replace AC filters monthly from June through September.
Ragweed dominates Philadelphia's fall allergy season. Counts peak in September and can remain elevated through October depending on when the first frost arrives. Mold spore counts also spike as fallen leaves decompose across the city's parks, rowhome-lined streets, and suburban neighborhoods. The combination of ragweed pollen and fall mold makes September one of Philadelphia's worst allergy months.
Top allergens: Ragweed, mugwort, mold spores, pigweed
Severity: Moderate to high (ragweed can be very high in September)
Tip: Fall in Philadelphia is beautiful but deceptive for allergy sufferers — pleasant weather encourages outdoor time right when ragweed peaks. Check counts daily and premedicate before spending time outdoors.
The first hard frost — typically in late October or November — kills ragweed and ends outdoor pollen season. November and December are Philadelphia's lowest outdoor allergen months. However, the transition to sealed windows and full-time heating reactivates indoor allergen issues in the city's older housing stock. Natural Christmas trees can introduce mold spores into homes.
Top allergens: Indoor mold, dust mites, pet dander
Severity: Minimal (outdoor), low to moderate (indoor)
Tip: Use the post-frost window to deep clean — vacuum with HEPA filters, wash all bedding in hot water, and address any basement moisture before sealing up for winter.
Philadelphia has one of the most advanced pollen monitoring systems in the Northeast. The Asthma Center has tracked daily pollen and mold counts for the Philly region since 1990 and installed an AI-powered pollen sensor in 2020 — one of the few in the country. Check their daily readings before planning outdoor activities, especially during peak tree pollen (April–May) and ragweed (September) seasons. This local data is more accurate for Philadelphia than national forecast models.
Philadelphia's iconic rowhome architecture creates unique indoor allergen challenges. Shared walls mean moisture problems in one unit can affect adjacent homes. Basements in older rowhomes are notoriously damp — ideal for mold growth that can permeate upper floors through the building envelope. Run a dehumidifier in the basement year-round (aim for below 50% humidity), ensure dryer vents exhaust outdoors, and address any visible mold promptly. If you rent, document moisture issues and request remediation from your landlord.
Fairmount Park is one of the largest urban park systems in the country, with over 2,000 acres of dense tree canopy. The Wissahickon Valley is a treasured natural area. Both are major pollen sources from March through July. If you exercise on the Schuylkill River Trail, Forbidden Drive, or Kelly Drive, shift your schedule to late afternoon or evening when pollen counts drop. Morning runs during peak season (April–May) expose you to the highest pollen concentrations of the day.
Philadelphia's Mid-Atlantic humidity regularly exceeds 70% during summer months, creating ideal conditions for mold growth both indoors and outdoors. Mold spore counts peak in July and August and are a significant but often overlooked allergen in the city. If your allergy symptoms persist or worsen during summer even as grass pollen drops, mold may be a major trigger. Air conditioning is essential — not just for comfort but to reduce indoor humidity. Clean AC units and filters monthly during summer to prevent them from becoming mold reservoirs.
Philadelphia's position between the Schuylkill and Delaware Rivers, surrounded by the low-lying Delaware Valley, creates microclimates where warm, humid air can trap pollen at lower altitudes for extended periods. Days when warm air stagnates over the region — common in late spring and summer — tend to produce the worst pollen counts. Watch for weather forecasts mentioning temperature inversions or stagnant air patterns and plan to stay indoors on those days.
If you've been cycling through Zyrtec, Claritin, and Flonase every spring and fall without lasting relief, you're managing symptoms without addressing why your immune system overreacts. HeyAllergy's board-certified allergists can identify your specific triggers through blood testing and create a personalized treatment plan with HeyPak® sublingual immunotherapy drops formulated for the Philadelphia region's allergens. Most patients notice improvement within 3–6 months. Book a telemedicine consultation from anywhere in the greater Philadelphia area — no clinic visit needed, no waitlist.
April through May is typically the worst period, when tree pollen from oak, birch, maple, and hickory peaks and overlaps with early grass pollen. September is also severe due to ragweed, which is the dominant fall allergen in the Delaware Valley. Summer months bring elevated mold spore counts due to Philadelphia's humidity.
Outdoor pollen season runs from approximately March through October — a 7–8 month season. Winter brings genuine outdoor pollen relief, but indoor allergens including dust mites, mold, pet dander, and mouse allergens intensify in Philadelphia's older rowhomes and apartments when heating systems run and windows are sealed for months.
Philadelphia's Mid-Atlantic location creates hot, humid summers that are ideal for mold growth. The city's large stock of older rowhomes with damp basements and limited ventilation compounds the problem indoors. Mold spore counts peak in July and August and are a significant but often underappreciated allergen for Philadelphia residents. If symptoms persist when pollen is low, mold is likely a trigger.
Yes. HeyAllergy provides telemedicine appointments with board-certified allergists licensed in Pennsylvania. You can book a virtual consultation, have allergy blood tests ordered at a local lab, receive a diagnosis, and start treatment — all without visiting a clinic. No waitlist.
HeyAllergy's HeyPak® sublingual immunotherapy drops are customized based on your blood allergy test results and formulated with allergens specific to the Philadelphia region — including oak, birch, maple, Timothy grass, ragweed, dust mites, and mold. You place drops under your tongue daily at home. Over 3–6 months, your immune system builds tolerance, reducing symptoms and medication dependence.
HeyAllergy accepts Medicare and most major PPO health plans, including United Healthcare, Anthem Blue Cross, Blue Shield, Cigna, Aetna, Humana, Oscar, and Tricare. Telemedicine benefits vary by plan — contact your insurance provider with HeyAllergy's Tax ID (85-0834175) to confirm your specific coverage.
Philadelphia sits in the Mid-Atlantic Coastal allergy region where warm, humid air from the south meets cooler northern air masses. This convergence can trap pollen at low altitudes for extended periods. The city's massive park system (Fairmount Park, Wissahickon), river-valley geography, and aging rowhome housing stock create a combination of intense outdoor pollen exposure and significant indoor allergen challenges that is distinctive among major East Coast cities.
HeyAllergy has no waitlist. You can book an online appointment at a time that works for you and see a board-certified allergist via secure video consultation — typically within days, not weeks. Available for residents throughout Philadelphia and the surrounding counties including Delaware, Montgomery, Chester, and Bucks.
Philadelphia occupies a distinctive position in the Mid-Atlantic Coastal allergy region — a zone where warm, humid air masses from the south regularly collide with cooler northern systems. This meteorological convergence creates conditions that can trap pollen at low altitudes for extended periods, prolonging high-count days beyond what residents of purely northern or southern cities experience. The result is an allergy season that stretches 7–8 months, from late February through October, with some of the highest pollen concentrations in the Northeast.
The Delaware Valley's geography amplifies this effect. Philadelphia sits between the Schuylkill and Delaware Rivers in a relatively low-lying basin, surrounded by the wooded hills of the Wissahickon, the expansive Fairmount Park system, and the densely landscaped suburbs of the Main Line, Montgomery County, and Bucks County. Prevailing winds carry pollen from these surrounding green areas into the urban core, creating a layered allergen environment that combines urban and suburban pollen sources.
Fairmount Park is one of the largest urban park systems in the United States, spanning over 2,000 acres of dense tree canopy, meadows, and river-adjacent green space. The Wissahickon Valley alone contains over 50 species of trees. While these parks are essential to Philadelphia's quality of life and identity, they're also concentrated allergen sources during pollen season. Oak, maple, birch, hickory, and ash trees produce heavy pollen loads from March through May, and grass lawns contribute from May through July.
The Schuylkill River Trail, Kelly Drive, and Forbidden Drive are among the most popular recreation paths in the city — and they run directly through the highest-pollen areas. For the hundreds of thousands of Philadelphians who run, bike, and walk these trails during spring and summer, strategic timing (late afternoon rather than early morning) can meaningfully reduce allergen exposure during peak season.
Philadelphia's housing landscape is dominated by rowhomes — the iconic brick and stone attached houses that define neighborhoods from South Philly to Fishtown to Germantown. While architecturally distinctive and culturally significant, rowhomes present specific indoor allergen challenges. Many were built in the late 19th or early 20th century with materials and designs that predate modern moisture management. Basements in older rowhomes are notoriously damp, creating ideal conditions for mold growth that can affect the entire structure.
Shared walls between units mean that moisture or pest problems in one home can affect adjacent properties. Mouse allergens are a documented issue in older Philadelphia neighborhoods and contribute to allergic sensitization. Cockroach allergens are present in multi-unit housing. During Philadelphia's cold winters, these older homes seal up with limited ventilation, concentrating dust mites, mold spores, and other indoor allergens in living spaces for months.
Philadelphia's summers are notoriously hot and humid, with humidity levels regularly exceeding 70%. This creates ideal conditions for outdoor mold growth — on building exteriors, in parks, and along the rivers. Indoor mold thrives in poorly ventilated rowhome basements, bathrooms, and around window units. The Asthma Center, which has monitored Philadelphia's pollen and mold counts since 1990, consistently documents elevated mold spore levels from June through August.
For allergy sufferers, summer mold represents a significant but often overlooked trigger. Patients who feel relief as grass pollen drops in July but then experience worsening symptoms through August are often reacting to mold spores rather than pollen. Air conditioning is essential in Philadelphia during summer — not just for comfort but as a medical necessity for controlling indoor humidity and filtering mold spores from the air.
Getting to specialist appointments in Philadelphia means navigating the Schuylkill Expressway, I-76, I-95, or SEPTA — none of which are known for reliability or convenience. Traditional allergy clinics in Center City and the suburbs often have multi-week wait times for new patients, and allergy shot schedules requiring weekly visits are difficult to maintain with Philadelphia's commuting realities.
HeyAllergy eliminates these barriers. Residents throughout Philadelphia, Delaware County, Montgomery County, Chester County, and Bucks County can see a board-certified allergist from home via secure video consultation. Comprehensive blood allergy tests can be ordered to a convenient local lab, and a personalized treatment plan — including prescriptions and HeyPak® sublingual immunotherapy drops — can begin without a single in-person visit.
HeyPak® is particularly well-suited for Philadelphia patients because the drops are customized based on your specific test results and the allergens endemic to the Delaware Valley region — including local tree, grass, weed, mold, and indoor triggers. They're mailed directly to your door, taken daily under the tongue, and monitored through follow-up telemedicine visits. No needles, no Schuylkill Expressway, no waitlist.
If your allergy symptoms stretch across multiple seasons, over-the-counter medications aren't providing adequate relief, you experience recurring sinus infections, allergies are affecting your sleep or productivity, you have both allergies and asthma, your symptoms persist or worsen during humid summer months when pollen is lower, or you suspect your rowhome may be contributing to indoor allergy symptoms, it's time to see a board-certified allergist.
HeyAllergy accepts Medicare and most major PPO health plans, making expert allergy care accessible for residents throughout the greater Philadelphia area.
