About one in four U.S. adults has a seasonal allergy, and if your symptoms feel worse or more persistent than you remember, you’re not imagining it. The pollen season across the country has lengthened by an average of 20 days since 1990, meaning allergens are in the air earlier, later, and in higher concentrations than they were a generation ago. What’s triggering your symptoms right now depends on the time of year, where you live, and what’s happening both outdoors and inside your home.
Which Pollen Is in the Air Right Now
Different plants release pollen on a predictable schedule, and knowing which one is peaking narrows down your trigger fast. Tree pollen dominates from March through May and is the most common spring allergen. Grass pollen picks up in late spring and runs through early summer. Ragweed, one of the most aggressive allergens, releases massive amounts of pollen from August through November depending on your region.
These windows overlap, so if you’re caught between seasons you could be reacting to more than one type of pollen at the same time. A dry, windy day sends pollen counts soaring, while a calm, rainy morning temporarily washes it out of the air. Checking your local pollen forecast (available through most weather apps) tells you exactly which counts are elevated on any given day.
Why Thunderstorms Make It Worse
If your symptoms spike before or during a storm, there’s a specific reason. In the hours before a thunderstorm, large amounts of pollen are released into the air. The moisture and electrical charge from the storm then rupture those pollen grains into fragments small enough to bypass your nose and travel deep into your lungs. Cold downdrafts push those fragments to ground level right where you’re breathing. One study found that on thunderstorm days, asthma-related emergency room visits increased by about 14.5% for every unit increase in precipitation rate. Even if you normally just get a runny nose from pollen, a thunderstorm can turn that into chest tightness or wheezing.
Indoor Triggers You Might Be Overlooking
Not all allergy flares come from outside. Dust mites thrive when indoor humidity stays above 40% to 50%, and they reproduce rapidly as humidity climbs higher. In humid climates or during summer months when windows stay open, mite populations surge. Conversely, running air conditioning pulls moisture from indoor air, which can suppress mites but may also recirculate dust and mold spores trapped in filters.
Pet dander is another persistent indoor allergen. The particles are microscopic and jagged, which means they stay airborne longer than other allergens and cling stubbornly to furniture, bedding, and clothing. Pet dander can even travel into homes that have never had a pet, carried in on jackets and bags. If your symptoms don’t follow a clear seasonal pattern, an indoor trigger is a strong possibility.
Why You Have Allergies Now When You Didn’t Before
Developing allergies as an adult is common and catches many people off guard. Every exposure to an allergen gives your immune system another opportunity to build a reaction to it. At some point, you cross a threshold and start producing enough of the antibodies (called IgE) to trigger symptoms. This can happen at any age.
Several things accelerate the process. Moving to a new region introduces your immune system to an unfamiliar ecosystem of plants, molds, and insects. Hormonal shifts during pregnancy, menopause, or other life stages change how your immune system responds to allergens. Chronic stress doesn’t cause allergies directly, but it weakens immune regulation enough that something previously tolerable suddenly becomes a problem. If you’ve recently relocated, gone through a major life change, or been under sustained pressure, any of those could explain why your body is reacting now.
What’s Actually Happening in Your Body
When pollen or dander enters your nose, your immune system treats it as a threat. In sensitized people, antibodies sitting on the surface of immune cells called mast cells recognize the allergen and signal those cells to release histamine and other inflammatory chemicals. This happens within minutes.
Histamine is the direct cause of the symptoms you feel. It triggers nerve endings in your nose (sneezing and itching), ramps up mucus production (runny nose), and dilates blood vessels in your nasal tissue (congestion). This early-phase reaction occurs in more than 90% of people with confirmed allergic rhinitis and positive skin tests. In many cases, a second wave of inflammation follows hours later, which is why symptoms can linger well after you’ve gone indoors.
Allergy Seasons Are Getting Longer
Climate change is measurably extending allergy season. The freeze-free growing season has lengthened in 87% of 198 U.S. cities analyzed, by an average of 21 days since 1970. Some cities have seen dramatic shifts: Reno, Nevada gained 100 additional frost-free days, Medford, Oregon gained 68, and Boise, Idaho gained 55. A longer growing season means plants start producing pollen earlier in the spring and continue later into the fall. The Northwest and Southwest have seen the biggest changes, with growing seasons stretching by 31 and 22 days respectively.
Warmer winters also affect indoor allergens. Rising winter temperatures in some regions allow dust mites to survive indoors year-round instead of dying off during cold, dry months. The net result is that both outdoor and indoor allergy seasons are expanding.
Foods That Trigger Symptoms During Pollen Season
If your mouth itches or your lips tingle when you eat certain raw fruits or vegetables, you may be experiencing oral allergy syndrome. Your immune system confuses proteins in certain foods with the pollen you’re allergic to, causing a cross-reaction.
- Birch tree pollen (spring): reactions to pitted fruits, carrots, peanuts, almonds, and hazelnuts
- Grass pollen (late spring/summer): reactions to peaches, celery, tomatoes, melons, and oranges
- Ragweed pollen (late summer/fall): reactions to bananas, cucumbers, melons, and zucchini
These reactions are usually mild, limited to itching or tingling in the mouth, and resolve quickly. Cooking the food typically eliminates the cross-reactive protein.
It Might Not Be Allergies at All
Not every stuffy nose is an allergic reaction. A condition called vasomotor rhinitis produces many of the same symptoms, including congestion, runny nose, and postnasal drip, but it’s triggered by irritants rather than allergens. Strong odors, temperature changes, dry air, cigarette smoke, and even spicy food can set it off. The key difference is that no immune reaction is involved. People with vasomotor rhinitis have normal antibody levels and negative skin tests.
If over-the-counter antihistamines don’t help your symptoms at all, irritant sensitivity is worth considering. The distinction matters because the treatments differ. Allergic rhinitis responds to antihistamines and allergen avoidance, while vasomotor rhinitis often responds better to nasal sprays that target inflammation directly. A skin prick test or blood test measuring allergen-specific antibodies can confirm which type you’re dealing with.