Understand St. Louis Pollen Counts & Allergy Index

St. Louis Allergy Index & Pollen Count

Today’s pollen count & allergy index in St. Louis, Missouri. Learn about the different types of pollen in St. Louis, including tree pollen, grass pollen, ragweed pollen, and mold that can be causing seasonal allergies. Learn how to interpret pollen counts and the allergy index of St. Louis to live more comfortably throughout seasonal allergies with the help of St. Louis’s favorite Allergist Dr. Sonia Cajigal.

“Had my first appointment with Dr. Cajigal. She’s wonderful. A different doctor had said there wasn’t much I could do for my allergies, except maybe move out of state. I was desperate and came to the doctor for help. She listened and was very thorough in her diagnosing my problems. I’m not better yet but I’m very pleased with how this appointment went and I’m optimistic about my health!”

– Rosana B, November 2021

Pollen Allergist Sonia Cajigal of St. Louis Family Allergy in St. Louis, Missouri
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Pollen Count & Allergy Index St. Louis

Today’s Pollen Count

Types of Pollen Counts

Interpreting Pollen Counts

Seasonal Allergy Relief

Today’s Pollen Count in St. Louis MO

View today’s pollen count in St. Louis MO on Pollen.com.
Today's pollen count in St. Louis MO

St. Louis MO Allergy Index

View St. Louis’ allergy index for today and the 5-day allergy forecast on Pollen.com.

Allergy forecast for St. Louis MO

Pollen Counts & Allergy Index Explained

If you have allergies, daily pollen counts in St. Louis can help give you some idea of how much allergen is currently present in the air. Levels of tree pollen, grass pollen, and ragweed pollen are reported most often, while some reports also cover mold and dust. Generally the higher the count, the greater the chance that individuals with allergies will experience symptoms and discomfort. There is variation in how reporting is done, especially on a quantitative basis, but most systems present counts as “low”, “medium”, or “high” and some differentiate by allergen (oak tree pollen vs. ragweed pollen, for example).

A pollen count or mold count is based on the measurement of the number of grains of pollen or mold spores per cubic meter of air collected in real-time or over a recent time period such as the last 24 hours. This ‘real-time’ data is combined with current weather patterns and historic data in the St. Louis area to estimate allergy forecasts for the coming days. Like regular weather forecasts, pollen counts and an allergy index are imperfect for a number of reasons that we discuss in more detail in the sections below. That said, pollen counts can help you make decisions about your day and help you prepare for allergy symptoms if you know what you’re allergic to, and many allergists (ourselves included) recommend using pollen counts as you navigate seasonal allergies.

Seasonal Allergy Relief

in St. Louis, Missouri

Tree pollen count in St. Louis MO

Common St. Louis Pollen Counts

Most allergy index report an overall pollen count that’s an aggregate of tree, grass, ragweed, and sometimes mold counts. Depending on what you’re allergic to, how sensitive you are to a specific allergen, and how your symptoms develop when you’re exposed to a specific allergen, the overall pollen counts in St. Louis may accurately reflect your experience or they may not. As an example, you may be most sensitive to tree pollen or grass or maybe ragweed — these allergens peak during different seasons in St. Louis, so more detailed allergen reports focused on tree pollen, grass pollen, ragweed, or mold can be helpful if your allergies are specific.

Tree Pollen St. Louis

Trees release pollen to reproduce throughout the St. Louis Missouri springtime, which typically spans from March into May. Common culprits of tree pollen allergies in St. Louis include oak trees, cedar trees, hickory trees, walnut trees, and ash trees. Tree pollen allergy symptoms in St. Louis will differ from person to person, and can include:

  • Coughing
  • Frequent sneezing
  • Runny nose
  • Itchy, watery, red eyes
  • Sinus pressure
  • Asthma symptoms

Grass Pollen St. Louis

Grass pollen season in St. Louis typically runs from May through mid-July. If you’re allergic to grass pollen, symptoms can include:

  • Congestion
  • Coughing, wheezing
  • Runny nose, nasal congestion
  • Scratchy throat, excess saliva
  • Itchy, stinging, watery eyes
  • Fatigue
  • Trouble Sleeping
  • Asthma symptoms

Ragweed Pollen Count St. Louis

Ragweed pollen is also prevalent in St. Louis Missouri, and is a prime cause of allergies from late August through to the first frost of late fall / early winter. Ragweed pollen is a common allergen in St. Louis primarily because of its microscopic spore size – just one ragweed plant produces more than one billion grains of pollen per season, and ragweed spores are known to travel for hundreds of miles when carried with the wind. Symptoms of ragweed pollen allergies are similar to grass pollen.

Mold Count St. Louis

While not technically a pollen, mold spores spread through the air like pollen and are often reported alongside pollen in allergy indexes. They persist in damp, humid, and cool environments especially in decaying plant matter, which are relatively common in St. Louis Missouri’s wetter seasons. For the average household, mold can be present in felled leaves, grass clippings, compost piles, and rotting or wet wood. Mold allergens are least prevalent in the St. Louis Missouri winter and become more prevalent as temperatures warm again. Mold allergies have all of the symptoms of grass and ragweed allergies, but can also include hives, worsening eczema, swollen eyelids, wheezing, and upset stomach.

Seasonal Allergy Relief

in St. Louis, Missouri

Grass pollen in St. Louis MO park

Interpreting Pollen Counts & Allergy Indexes

Pollen counts are formulated using measurement devices called pollen counters. Pollen counters are placed on the tops of buildings where they collect air samples through a variety of methods. Pollen in the air is collected on some type of surface, and the amount of pollen collected is analyzed by a trained technician. Calculations are then made to estimate how much pollen is present in the air based on what is collected over a specific period of time. Pollen levels (low, medium, high) are reported based on averages of airborne pollen collected throughout previous years. There are accuracy limitations when it comes to pollen collecting, counting, and reporting. Pollen counters are intentionally placed to collect a representative sample of air in the area, and even though pollen can distribute across many miles, the local plants and conditions near the pollen counter can be overrepresented while unique spots throughout the reporting area can be underrepresented. Another source of inaccuracy is time of day. Some pollens, such as grass, are mostly active in the morning hours and are less so later in the day. Fast changing weather conditions can also alter actual pollen counts in a big way, rendering the day’s established counts inaccurate. Even without these factors, the types and amounts of pollen collected can also change over the course of a day and from day to day.

Relief from Seasonal Allergies

Pollen counts and allergy forecasts can help you to better navigate life with allergies, and there are several other easy steps that you can take to live comfortably despite seasonal allergies in St. Louis.

Learn What You’re Allergic To

Allergy symptoms tend to be relatively consistent from allergen to allergen. In other words, an allergy to oak tree pollen can look a lot like a ragweed allergy, but you’re not necessarily allergic to both if you’re allergic to one of them. Understanding exactly what you’re allergic to can make it much easier to navigate seasonal allergies in St. Louis and know what you should (and should not!) be avoiding. This is where allergy testing comes in. Dr. Cajigal can help you determine if your symptoms are caused by allergies and pinpoint what you’re allergic to so you can find relief. Diagnosis starts with a thorough medical history, and usually involves skin or blood tests to determine your allergic triggers. Once you’re aware of what’s causing your allergies, there are steps you can take to minimize exposure to allergens, effectively manage allergic reactions if they occur, and prevent certain allergic reactions altogether.

Limit Your Exposure to Airborne Allergens

  • Check your local pollen counts whenever you check the weather
  • Limit outdoor activities during times of high pollen counts
  • Wear sunglasses and a wide brimmed hat to reduce pollen exposure when outdoors
  • Allergy-Proof Your Home

    • Keep windows closed during high pollen and mold seasons
    • Steam clean carpets or remove carpets altogether
    • Avoid air drying laundry outside
    • Change clothes as soon as you get home if you’ve spent a lot of time outdoors
    • Keep pets out of the bedroom to reduce pet dander in your bedding
    • Vacuum with a HEPA filter to reduce dust in your home
    • Wash your bed linens and pillowcases in hot water and detergent frequently to reduce allergens
    • Use dust mite proof covers for pillows, comforters, duvets, mattresses and box springs
    • Men should shave frequently to prevent pollen from gathering in their facial hair

    Manage Symptoms with Medications

    There are a number of over-the-counter and prescription medications that can help relieve allergic rhinitis symptoms. These include:
    • Antihistamines
    • Decongestants
    • Nasal corticosteroids (nasal spray)
    • Leukotriene receptor antagonists
    • Cromolyn sodium
    Be sure to discuss any medications with your allergist prior to using them. Medications to relieve seasonal allergic rhinitis, for example, are most effective if you start taking them before pollen is in the air, prior to allergy symptoms developing.

    Consider Allergy Shots

    Allergy shots are also an option if you’re looking for long-term, ongoing symptom relief from seasonal allergic rhinitis.


    [1] American College of Allergy, Asthma & Immunology: https://acaai.org/ [2] Asthma and Allergy Foundation of America: https://www.aafa.org/
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    "Dr. Cajigal was friendly, professional, and informative. She took the time to explain the tests and what was going on with my allergies. She is so knowledgeable and really cared about how I was feeling. I would highly recommend this practice if you suffer from allergies and asthma."

    - Sue D, July 2020

    “Dr Cajigal is a great listener. She trusts her patients instead of treating them as if they are not the experts of their own bodies. I really appreciate that (many doctors do not have that quality). She also immediately treats the symptoms instead of waiting to see if things clear. I use her for my children and myself. We have never left her office feeling as if it was a waste of time.”

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