Boise, Idaho, has become the nation's pollen capital, scoring a perfect 100 out of 100 on the Asthma and Allergy Foundation of America's annual allergy rankings. The city rocketed from 95th place last year, marking a dramatic shift in which areas of the country are hit hardest by seasonal allergies. The change reflects broader climate patterns affecting pollen production across the United States, with 35 of the 100 cities analyzed reporting worse average pollen levels compared to the previous year .

The surge in Boise's ranking comes as no surprise to allergists tracking environmental trends. Heavy rainfall and long-lasting warm weather over the past 12 months have driven up pollen counts in areas that previously had lower levels. More rain means more plant growth, and warmer temperatures extend the period during which plants release pollen into the air. San Diego, California, took second place, jumping from 97th place last year, while Tulsa, Oklahoma, rounded out the top three .

About 25.7% of adults and 18.9% of children in the United States have seasonal allergies, with tree pollen being the most common trigger . When pollen enters the body, the immune system mistakenly identifies it as an invasive protein and releases histamine, a chemical that causes the familiar symptoms of sneezing, runny nose, and watery eyes. For many people, these symptoms significantly impact quality of life, causing daytime sleepiness and difficulty concentrating .

What's Driving the Shift in America's Allergy Geography?

Climate change is reshaping where allergies hit hardest. Previously, the worst allergy cities were concentrated in the Southeast, where warmer and more humid climates naturally support pollen production. But in 2025, areas in the West experienced more extreme weather events, driving more plant growth and longer pollen seasons, particularly for grass and weed pollen. This shift has caused many Western cities to jump dramatically in the rankings .

The problem extends beyond spring. While tree pollen peaks in April and grass pollen emerges in early summer, ragweed appears in the fall. Year-round indoor allergens like pet dander, dust mites, and mold create a continuous exposure cycle for many people. In regions like San Diego, dust mites thrive year-round, particularly between October and March, because the mild climate provides the humidity these allergens need to reproduce .

"Climate change is driving some areas to have a nearly year-round cycle of pollen production or experience major pollen explosions multiple times a year due to extreme weather. These longer and more intense pollen seasons mean allergy symptoms may start earlier, last longer, and be more difficult to control," warned Sanaz Eftekhari, vice president of the Asthma and Allergy Foundation of America.

Sanaz Eftekhari, Vice President, Asthma and Allergy Foundation of America

How to Manage Allergy Symptoms Before They Start?

The key to controlling allergies is preparation. Experts recommend starting allergy medications before symptoms begin, rather than waiting until you're already miserable. This proactive approach is especially important for corticosteroid nasal sprays, which take about seven to 10 days of regular use to become fully effective.

• Start medications early: Begin taking allergy medications before pollen season peaks in your area, even if you don't have symptoms yet. This gives medications time to build up in your system and prevents symptoms from developing in the first place.
• Use corticosteroid nasal sprays consistently: Sprays like fluticasone (Flonase) and triamcinolone (Nasacort) are considered the single most effective treatment for moderate to severe allergy symptoms. They block allergic reactions and can even ease eye symptoms, but require consistent daily use throughout the season.
• Combine medication types for better coverage: Oral antihistamines like cetirizine (Zyrtec), fexofenadine (Allegra), and loratadine (Claritin) work well alongside nasal sprays and eye drops. Second-generation antihistamines are preferred over older options like diphenhydramine (Benadryl) because they cause less drowsiness and are safer for long-term use.
• Choose the right antihistamine for your needs: If you need fast relief, antihistamine nasal sprays like azelastine (Astepro) work quickly. For sustained symptom control, oral antihistamines taken daily are more effective. The medication that works best varies from person to person, so you may need to try different options.
• Monitor pollen counts and adjust timing: Pollen levels are typically lower between 4 a.m. and noon during spring and summer, while counts spike in the afternoon and evening. Schedule outdoor activities for early morning when possible, and check pollen forecasts through resources like pollen.com or the National Allergy Bureau.

If you've been taking a particular antihistamine regularly and it's no longer controlling your symptoms, don't assume it has stopped working. The issue may be that pollen levels are higher this year, you need an additional medication, or you're taking an insufficient dose. Consulting with your doctor or an allergist can help identify the right adjustment .

Can You Keep Allergens Out of Your Home?

Once pollen counts rise in your area, the goal is to create an allergen-free zone indoors where you can find relief. The most effective strategy is keeping windows and doors closed during high pollen days and using air conditioning or fans to circulate air instead. This simple step prevents pollen from entering your home in the first place .

Air purifiers with HEPA (high efficiency particulate air) filters can remove at least 99.97% of pollen, dust, mold, and other airborne particles as small as 0.3 microns, according to the Environmental Protection Agency. If you already own a purifier, now is the time to replace the filter so you're starting allergy season with a fresh one .

Allergens can also travel indoors on clothing, hair, and pets. Taking a shower, washing your face, and changing into clean clothes after spending time outside helps remove pollen before it settles in your home. Washing pillows, blankets, rugs, and curtains periodically throughout the season removes allergens that linger on fabrics. Don't hang clothes outside to dry during peak pollen periods, as they'll collect pollen .

Using allergen-proof mattress and pillow covers and bathing pets regularly if you're allergic to pet dander further reduces indoor allergen exposure. Saline nasal rinses using a neti pot or squeeze bottle can flush allergens from nasal passages and relieve congestion, though you should always use sterile or distilled water to avoid introducing harmful pathogens .

When Should You See an Allergist?

If over-the-counter medications and environmental controls aren't providing relief, or if your symptoms are disrupting your daily life, it's time to see an allergist. An allergist can perform skin prick testing or blood tests to identify your specific triggers. During skin testing, a provider places a drop of allergen on your skin via a small prick. If you're allergic, you'll develop a mosquito bite-sized bump within minutes. Blood tests measure IgE (Immunoglobulin E), a type of antibody your body produces during allergic reactions .

For patients whose symptoms aren't controlled by medication or who experience side effects, immunotherapy may be recommended. Allergy shots work by gradually exposing your immune system to small amounts of allergens, helping your body build tolerance over time. Treatment typically involves weekly injections for the first six months, followed by maintenance doses for three to five years. While this requires a time commitment, many people experience significant symptom improvement .

"It's easier to play a good defense. It's harder to catch up once the symptoms start rolling," explained Grace Koo, assistant professor of medicine in the Division of Allergy, Pulmonology and Critical Care Medicine at Vanderbilt University Medical Center.

Grace Koo, Assistant Professor of Medicine, Vanderbilt University Medical Center

Chronic exposure to allergens tends to worsen over time, particularly as your immune system weakens with age. Additionally, prolonged sinus congestion from allergies can lead to sinus infections, which are sometimes unnecessarily treated with antibiotics. Early evaluation and treatment can prevent symptoms from escalating and help you maintain better quality of life, sleep, and breathing throughout allergy season .

The bottom line: allergies are increasingly difficult to manage without a plan. Whether you live in Boise or another high-pollen city, starting treatment early, controlling your indoor environment, and working with a healthcare provider to find the right medication combination can make the difference between a miserable season and one where you can actually enjoy spring and summer .