Asthma and Allergy Forecast
The Asthma and Allergy Forecast tool uses advanced data to determine potential asthma and allergy triggers on a given day, including the pollen count today. It also provides data on the daily risk and spread of the flu virus.
What the Forecast Means
Asthma index: a combination of weather factors that can trigger asthma symptoms. A higher index value means more people with asthma will potentially be affected by weather factors, such as changes in temperature or allergens in the air.
Allergy index: a combination of weather factors and plant growth stages that increase the release and airborne spread of pollen. A higher index value represents a high pollen count and/or spread of pollen.
Flu index: a combination of historical flu data and temperatures. The index represents the degree to which transmission of the virus is favorable. A higher flu index means the spread of a flu virus is very favorable, assuming the disease is present.
The colored bars atop each index represent where the data currently stands based on the forecast date. Each index is scaled from 0 to 10, with 0 being very low and 10 being very high. The further to the right the tick mark is, the higher the index level.
This tool allows you to have a personalized index for the pollen count today in your area. Do you need an allergy forecast in NYC? How about a Dallas allergy report? Or perhaps you’re looking for an Austin, Texas allergy report or an Oklahoma City allergy report? The index provides you with an asthma and allergy report so you can find out if allergies are bad right now in your area. No matter where you live, we’ve got you and your local weather covered.
At a Glance: Weather Forecast
- Environmental triggers. Respiratory health can be influenced by allergens (such as pollen), air pollution (fine particulate matter), high humidity, and extreme heat.
- Weather effects. Cold, dry air can cause bronchial spasms. Thunderstorms can push small pollen particles deep into the lungs.
- Daily monitoring. Use apps to track daily pollen counts, mold levels, and barometric pressure.
- Protection indoors. Maintain indoor air quality by keeping windows closed and using air filters, dehumidifiers, or air conditioning.
- Longer seasons. Climate change is extending growing seasons, which is leading to more severe and prolonged allergies.
What Is the Pollen Count Today?
Pollen counts measure the pollen in the air on a given day. Scientists use air sampling devices to collect particles from the air and then analyze them. They identify types of pollen as well as how much of each is in the sample.
The pollen count covers a large area since pollen is airborne. It is measured by grains of pollen in a cubic meter. Government agencies, universities and commercial research institutions measure pollen counts to provide information to the public.
You can visit the National Allergy Bureau for daily pollen count information. Many local news websites and TV stations report the pollen count as well.
Pollen comes from blooming grasses, plants, trees and weeds. It is carried far and wide by the wind. You might be allergic to one kind of pollen and not another. Pollen counts vary with the weather and location.
Pollen allergies can differ from person to person. Symptoms include:
- runny nose
- nasal congestion
- sneezing
- coughing
- itchy or irritated eyes
- eye redness or swelling
- postnasal drip
- fatigue
People with allergic asthma may have difficulty breathing.
It is essential to know which types of pollen trigger your allergies. You may have grass, tree or ragweed pollen allergy. Your healthcare provider may recommend allergy testing, such as a skin test or allergen-specific blood tests. If testing confirms a pollen allergy, work together with your doctor to develop the best treatment plan for you.
Work with your doctor to craft a treatment plan that reflects your pollen allergy. Take steps to avoid exposure to pollen and treat allergy symptoms.
During longer allergy seasons with high pollen counts, allergy patients may find they need to use more medication. Talk with your healthcare provider, preferably a board-certified allergist. Adjust your allergy management plan or medication schedule.
What is the Air Quality Today?
Checking the pollen count is only the beginning. Air pollution and mold spores are also problems for people with asthma and allergies.
Fine particulate matter such as emissions from factories, power plants and vehicles contribute to air pollution. When inhaled, these particles can be powerful asthma triggers. They affect breathing and lung function.
Mold spores and seeds fly through the air starting in late spring. They peak during the summer with hot, humid weather. In the fall, they grow on decaying leaves, compost piles and grasses. Windy, rainy weather during any season can send mold spores airborne.
Visit AirNow.gov for Environmental Protection Agency (EPA) air quality status and alerts. The website also has apps available for smartphones and tablets. Air quality alerts can help you plan your daily activities and manage your asthma and allergy symptoms.
How Does the Weather Affect Asthma and Allergies?
Weather can significantly impact people with asthma and allergies.
Changing weather patterns alter barometric pressure. This can trigger sinus problems and make breathing harder if you have asthma.
Humid air is moist and heavy. When the air is stagnant, air quality goes down. This makes breathing harder for everyone. It can trigger an asthma and allergy flare-up since mold and bacteria grow better in moist environments. Humid weather can worsen allergy symptoms.
Hot weather often impacts air quality. Ozone can rise to dangerous levels, irritating your respiratory system. Increased vehicle traffic (especially trucks and buses), exhaust, smog and other pollutants can make breathing harder for people with asthma. Hot weather and lack of rain can lead to wildfires. Wildfire smoke and ash can irritate your eyes, nose, throat and lungs. The smoke can travel hundreds of miles, affecting people far away.
Cold, dry air may seem better for your breathing than hot, humid air. Unfortunately, breathing it in can make the bronchial tubes constrict and spasm as they try to keep airways open. This can make asthma symptoms worse.
Thunderstorms bring barometric changes, high humidity and winds that blow pollen and mold spores everywhere. This can lead to what’s called thunderstorm asthma. In addition, lightning generates nitrogen oxides that can impact ground-level ozone, irritating the lungs and airways. Hurricane, thunderstorms and other extreme weather can also bring on floods.
When is Pollen Season and How Does It Impact Asthma and Allergies?
For most people, pollen season is in the springtime and the fall. Most trees, grasses and flowers bloom in the spring and release pollen. (Southern states often experience earlier tree pollen seasons.) In the fall, ragweed pollen emerges. But depending on where you live, pollen may be present year-round.
Here’s a look at the four seasons and the weather factors that can contribute to asthma and allergies:
Spring
When most people think of allergy season, they think of springtime when plants come to life and pollen and mold invades the air. Warm weather and rainfall in spring aids plant growth. Showers may offer people with allergies and asthma a break. Moisture weighs down the pollen, keeping it on the ground. Depending on where you live, tree pollen levels are highest in April and May – earlier in southern and southwestern states. Grass pollen levels start to rise in late spring and early summer.
Summer
Grass pollen is at its peak from late May through early July, when dry, breezy conditions spread pollen. Thunderstorms with heavy winds can spread allergens further – especially small particles of pollen. These are inhaled more easily and can go deeper into the lungs.
Fall
Ragweed season begins in late summer, peaking in September and typically ending by the first frost. One of the most potent allergens, ragweed makes life miserable for many with itchy eyes and sinus symptoms. It can also trigger asthma. Mild temperatures, reduced humidity, and breezy conditions create the ideal environment for ragweed plants to release pollen.
Winter
People in the Southwestern United States, Mexico and Japan may experience winter allergies to the Ashe Juniper tree – commonly referred to as mountain cedar. This tree releases its pollen every year from December to February. For most other people living in areas with cold weather, winter is a welcome outdoor respite from allergies.
However, keep an eye on weather patterns. A mild winter can cause plants and trees to pollinate early – especially if there’s a lot of rain – leading to an early start to spring allergy season. Moisture from snowmelt in late winter can cause trees to produce more pollen when they bloom.
How to Monitor Pollen Season?
Keep track of the pollen count throughout the day, every day. Pollen counts tend to be higher in the morning. Trees, grasses and weeds release pollen first thing in the morning.
Outdoor mold is present during pollen season as well. Signs and symptoms of mold allergies are similar to pollen allergies. They include runny nose, nasal congestion, sneezing, sore throat, and watery or itchy eyes. People with asthma may feel tightened airways and trouble breathing. Even a tiny amount of exposure to mold can cause symptoms.
Sudden changes in the weather during pollen season can also affect your asthma and allergies. Temperature changes, humidity changes, and rain and wind from thunderstorms can inflame airways, leading to asthma flares.
People with respiratory conditions often breathe through the mouth. This can bring weather-related irritants directly to the lungs. It also doesn’t allow your nose to regulate the humidity and air temperature.
Pollen allergy seasons are trending toward becoming longer and more severe. This is due to changing weather patterns resulting from climate change. People with allergies may find they need to use more allergy medications to manage symptoms. Talk with your doctor about whether to adjust your treatment plan.
How Do You Manage Environmental Asthma and Allergy Triggers?
The key to managing asthma and allergies during any season is to know your triggers. Pollen might bother you a little bit, or it can make you feel miserable. You might find cold air ramps up your asthma symptoms.
Asthma and allergies are unique to each person. Here are some tips to help you manage environmental asthma and allergies:
- Use an app or weather forecasting site. Keep an eye on potential weather changes that might affect you. Check the pollen count, mold spore count, air quality index, humidity, temperature, and changes in barometric pressure. Sign up for alerts via email or text.
- Stay indoors and limit outdoor exercise when the pollen count is high or the air quality is poor. This includes when wildfire smoke may be present, even if it comes from hundreds of miles away.
- Wear a mask when gardening or cutting grass. This can limit exposure to pollen, mold spores and air pollution.
- Use a scarf to shield your mouth and nose in cold weather. The scarf warms and humidifies the air before you breathe it in, reducing shock to your airways.
- Keep humidity levels in your home steady. Air conditioning, dehumidifiers or humidifiers can help keep your airways from becoming inflamed.
- Take all your asthma medicines as prescribed. These help you control your asthma daily and during an asthma attack. Follow your Asthma Action Plan and your doctor’s recommendation for treatment.
- Use air filters indoors. These can reduce indoor allergens and particle levels. Pollen can come inside with open doors and windows. Mold, pet dander and dust mites are common indoor allergens. High efficiency particulate air (HEPA) filters are considered the most effective. They work best alongside other avoidance strategies and treatment plan.
How do You Manage or Treat Seasonal Allergic Rhinitis (Hay Fever)
Allergic rhinitis is commonly called hay fever. Seasonal allergic rhinitis is caused by exposure to outdoor allergens, including pollen from trees, grasses, weeds and other plants.
Symptoms include runny nose, nasal congestion, sore throat, itchy eyes, headache, fatigue and postnasal drip. Severe symptoms can impact asthma, causing coughing, wheezing and shortness of breath.
If you have allergic rhinitis symptoms, or your asthma is worsening during certain seasons, work with your doctor to identify allergy triggers. They may vary from person to person. Your doctor may recommend allergy testing.
Once you have identified your allergic trigger, develop a treatment plan based on the results. Then work to avoid those triggers.
5 Ways to Reduce Seasonal Allergy Symptoms
- Check pollen and air quality forecasts.
- Keep windows closed during high pollen days.
- Shower and change clothes after spending time outdoors.
- Use HEPA filtration when possible.
- Take medications as directed.
How Does Climate Change Impact Seasonal Allergies?
Many scientists and doctors think climate change is a factor behind extreme pollen seasons and a rise in seasonal allergies. Fueled by more mild winters and higher temperatures, plants are blooming earlier and for longer periods of time in many parts of the country.
A 2021 study found North American pollen seasons had already lengthened by about 20 days between 1990 and 2018, with pollen concentrations up about 21%. A 2022 modeling study projected pollen seasons could start up to 40 days earlier and last up to 19 days longer by the end of this century.
The extended growing season means higher levels of pollen in the air and worsened allergies for many people.
Many people with allergies notice worse seasonal symptoms as pollen exposure continues through a season. Researchers call this a “priming effect.” It’s when repeat exposures to pollen lower the threshold needed to trigger symptoms. The result? Reactions can feel more severe later in the season. The impact of this “priming effect” varies, so it’s worth tracking your own symptom patterns with your doctor.
During longer allergy seasons with high pollen counts, allergy patients may find they need to use more medication to manage symptoms. Talk with your doctor about whether you should adjust your allergy management plan or medication schedule.
Your doctor can also discuss whether allergen immunotherapy for pollen is right for you.
August 2026
Reviewed by:
Ashwin K. Shankar, MD, is a double board-certified pediatric and adult allergist/immunologist practicing in Dallas. A state and national speaker, mentor, consultant, advisor, and published author, he is dedicated to advancing evidence-based allergy and immunology care through patient education, advocacy, health equity, and innovation. Dr. Shankar is passionate about expanding access to high-quality care while mentoring the next generation of allergy and immunology professionals.
