Allergies In Philadelphia: Everything To Know

Written by Hannah Ward
Published: February 18, 2023
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Having allergies is never fun, especially since, depending where you live, they can occur almost all year round. Seasonal allergies are triggered by allergens such as pollen and mold. However, there are several different types of pollen — including tree pollen, grass pollen, and weed pollen. If you live in Philadelphia then you’re probably already aware that tree pollen is one of the main allergens in the area. But just which trees and plants are the biggest contributors to seasonal allergies? Is there anything that you can do to alleviate your symptoms? Read on to discover the answers to both of these questions and much more as we learn all about allergies in Philadelphia!

When is Allergy Season in Philadelphia?

The first thing we need to know is exactly when allergy season is in Philadelphia. However, the bad news is that allergy season in Philadelphia actually runs from spring right through to the first hard frost of the year. Despite this, the tree pollen season — the main allergen — usually lasts from March until May, although it is lasting longer and longer every year and becoming the new normal.

Although Philly has a long allergy season, it only ranks at 40 overall in 2022’s allergy capitals according to the Asthma and Allergy Foundation of America. Due to the tree pollen season it rises to 34 for the spring season but drops to 49 in the fall.

Allergy season in Philadelphia is almost year-round
Allergy season in Philadelphia runs from spring right through to the first hard frost of the year.


Plants that Cause Allergies in Philadelphia (By Season)

As we mentioned earlier, pollen is a major allergen, and there are several types of pollen which come from a wide variety of plants and trees. However, not every plant is an allergen at the same time of the year. So, from the trees that blossom in the spring to the weeds that grow in the fall, lets take a look at the common plants that cause allergies in Philadelphia.


Spring is the time for the trees to blossom as the weather changes to give us a hint of the summer to come. However, with the beginning of spring we have pollen from ash, oak, hickory, maple, walnut, and willow trees. Although in previous years the tree pollen season was largely finished by May it now often carries on into the early summer due to the rising temperatures.

black willow vs weeping willow
In spring Philadelphia allergy sufferers face problems from the pollen generated by trees such as willow.

©Axel Bueckert/


As spring gives way to the long, hot days of summer it’s time for the grass pollen to take center stage. Grass typically pollinates from mid-May to late June and early July and the effects of grass allergies are usually experienced in the late afternoon. The common grasses that trigger allergies in Philly are Bermuda, upland bent, winter bent, colonial bent, spreading bent, black bent, timothy, rye, orchard, red fescue, nodding fescue, clustered fescue, and soft brome.

Bermuda grass lawn
In Philadelphia summers grass pollen from common grasses such as Bermuda is prevalent.



Fall sees the leaves begin to turn as the temperatures begin to drop and the days shorten. However, as the flowers begin to die off the main things that thrive are weeds. You may be surprised to find that weeds are key allergens, and one of the most prolific is ragweed which is known for its ability to produce several million grains of pollen from a single plant. Ragweed allergies tend to last from the beginning of fall until the first frost, although symptoms are usually worse before midday. Other weeds that cause problems for allergy sufferers in the fall include wormwood, sagebrush, amaranth, and Pennsylvania pellitory.

ragweed plant
In the fall weed pollen from plants such as ragweed become key allergens in Philly.



Finally, the arrival of winter brings cooler weather and some respite from the majority of the seasonal allergies. However, the falling temperatures and the damp air is the perfect conditions for mold spores to thrive. They are often found on dead leaves, rotten wood, and in compost heaps.

How to Treat Allergies During the Philadelphia Allergy Season

If you do suffer from allergies then there’s no need to suffer in silence as there are a few steps that you can take to help to ease your symptoms. Although we know that it’s completely unrealistic to completely avoid your triggers the two main things that can help with your allergy symptoms are prevention and medication. Let’s take a closer look.

Allergy Season
Two main things that can help with your allergy symptoms are prevention and medication.

©Jim Vallee/


  • Stay indoors when the pollen count is high: When the pollen count is at it’s highest there is a greater chance of your allergy being triggered. Avoiding peak times can greatly reduce your exposure.
  • Close your windows and doors: Closing your windows and doors, especially at peak times, can prevent pollen from entering your home.
  • Avoid gardening: Although spending time in your garden is an enjoyable experience, avoiding gardening chores such as mowing the lawn and weeding will avoid stirring up allergens in the air. If you do spend time outdoors then it’s a good idea to wash your clothes as soon as you come inside as the pollen will have stuck to the fabric.
  • Avoid hanging out laundry: As above, pollen sticks to fabric so not hanging your laundry outside to dry can prevent pollen from being brought indoors.
  • Use a dehumidifier or a HEPA filter: The use of a dehumidifier or a HEPA filter can help to remove particles from the air and keep it cleaner.


  • Oral antihistamines: These are the most common type of treatment for allergies and there are several types available over the counter.
  • Nasal sprays: Also known as nasal corticosteroids, these are anti-inflammatory drugs that are often used to treat moderate to severe symptoms.
  • Speak to your doctor: Although you may think that you have your allergies under control it’s always a good idea to speak to a healthcare professional as they may be able to offer you an alternative treatment.

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Man with allergies
Man with allergy sneezing into handkerchief with blooming trees in background.

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About the Author

I have been writing professionally for several years with a focus on animals and wildlife. I love spending time in the outdoors and when not writing I can be found on the farm surrounded by horses, dogs, sheep, and pigs.

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