When Allergy Season Starts and Ends

April showers bring May flowers, but they also signal the start of allergy season. Or do they? Spring and summer aren’t the only times of year you can find yourself itching, sneezing or wheezing. In fact, they may not even be when your symptoms are at their worst.

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So, when does allergy season start and end, really? And how long does allergy season last? We asked allergist and immunologist Katherine Weller, MD.

The different allergy seasons

Generally, in the northern hemisphere, allergy season:

Begins in late winter or early spring (February to May) with tree pollen
Peaks in late spring and early summer (May to July) with a combo of tree and grass pollen
Ends in late summer or early fall (July to November) with weed pollen and mold spores

That’s what we expect, anyway. But the reality is often more complicated.

Let’s dive into the details and nuances of each season.

Spring

When temperatures start to warm up, tree pollen is released into the air and can be present all the way up until summer.

Dr. Weller reports that tree pollen counts are at their highest in the morning, which explains why you can fall asleep feeling fine and wake up the next morning with a sore throat. If you have central air conditioning, you may also notice that you’re more symptomatic when you’re outside.

Summer

Grass pollen peaks during the summer season and is at its worst on warm, windy days. And mowing the lawn? That’s an insta-allergy boost, if ever there was one!

Dr. Weller also notes that hot, humid places often see an increase in mold spores during the summer, too.

“Some molds prefer hot conditions,” she explains. “That means mold counts can get very high in late summer or early autumn, depending on where you live.”

Fall

During the fall, weed pollen is at its worst. But unlike tree pollen, it’s most likely to affect you between 10 a.m. and 3 p.m.

Ragweed is one of the most common fall allergens, and its pollen levels are typically highest during this season. Ragweed pollen can travel hundreds of miles, so even if you don't live near ragweed plants, you may still be affected by them.

But wait, there’s more! The wet soil and fallen leaves that make autumn so moody also bring an increase in mold allergies.

“Many mold spore counts are highest in damp, rainy conditions,” Dr. Weller reports.

Winter

While winter isn’t traditionally seen as part of allergy season, your personal triggers could make it just as bad as (or worse than) the other seasons.

Colder weather is a time for indoor allergens to take center stage. If you feel miserable that first week you run the heat in your house, it’s because all the allergens that have been collecting in your vents, carpets and furniture are getting stirred back up, like:

Add in a personal trigger, like a Christmas tree allergy, and ‘tis the season to be sneezing.

Is allergy season ever over?

Whether allergy season is ever truly over depends on your triggers. If you’re allergic to multiple allergens (what’s known as being polysensitized), you may have reactions year-round. In that case, relief can be hard to come by.

“Many people have year-round symptoms, with peaks in the warmer times of the year,” notes Dr. Weller. “In those cases, we often find out that they’re allergic to not only pollens and molds, but also dust mites or pet dander.”

Factors that can affect when allergy season is

So, is it allergy season right now? And how can you tell? Turns out, it’s not as simple as looking at a calendar. Dr. Weller says there are a lot of different factors that play a role in determining how crummy you feel.

Your immune health

Your immune health changes over time, which means that the way your body reacts to the same allergen could look very different from week to week or month to month. Your allergies could be worse because of:

An infection: Your immune system can become overstimulated if it’s dealing with allergens and illness at the same time. All that extra inflammation can mean bigger, more unpleasant reactions.
Chronic health conditions: Autoimmune conditions, like lupus, Sjögren’s disease or rheumatoid arthritis, can make you more sensitive to allergens. Ditto for health conditions that affect your lungs, like asthma and COPD. And smoking can have a similar effect.
High stress levels: Chronic stress can throw off your immune system. That’s in part because stress hormones, like adrenaline and cortisol, cause inflammation. That inflammation may make it harder to breathe and make your allergies worse.
Certain medications: If you take medications that suppress your immune system, like steroids, chemotherapy or anti-rejection drugs, you may experience fewer seasonal allergies.
Your microbiome: There’s a growing body of research on the role gut health plays in allergy severity. The less diverse your gut bacteria are, the harder seasonal allergies are likely to hit.

Weather

Weather patterns can cause allergens to peak earlier or later than expected. A cold, wet spring, for example, can delay tree pollen season and cause it to overlap with the peak of grass pollen season, making it a double whammy for allergic reactions.

“Rain washes pollen from the air, so rainy days tend to have lower pollen counts,” Dr. Weller explains. “Conversely, warm and breezy summer days typically have higher pollen counts.”

Location

Different allergies peak at different times, depending on where you live. In California, Bermuda grass is one of the most severe pollen allergens, and ragweed isn’t a big issue. Meanwhile, in Texas, mountain cedar trees play a major role in seasonal allergies.

“The cedar trees in Texas pollinate early in the year, in January and February,” Dr. Weller reports. “They can increase pollen counts in the air dramatically. So, winter allergies are likely to be worse in that region.”

Air quality

Allergies feel way worse when your airways are already dry or irritated. Even small things, like a scented candle, can amplify symptoms.

Other factors that can affect air quality — and make seasonal allergies more intense — include:

Smoke (from fireplaces, grills, factories or wildfires)
Vehicle exhaust
Agricultural products like pesticides
Construction dust
Household chemicals

Help is available

Allergies can make you feel miserable in any or every season. But it doesn’t have to be that way. Dr. Weller advises seeing an allergist if your symptoms:

Disrupt your sleep or daily life
Affect work, school or hobbies
Don’t get better with over-the-counter medicine

“We frequently see people who are needlessly not feeling well — and we can help,” Dr. Weller reassures. “Medication and some avoidance tips could make a big difference in your quality of life. So, don’t hesitate to reach out.”