Allergy season can begin as early as January in warmer parts of the country and last until the first hard freeze. The timing depends on where you live, the weather and which types of pollen trigger your symptoms.

If it feels like something is always blooming, you are not imagining it.

Trees, grasses and weeds release pollen at different times of the year. Just as one allergy season begins to fade, another can take its place.

The CDC says seasonal allergies affect as many as 60 million people in the United States each year. CDC

Quick Breakdown

• Winter and early spring: Tree pollen begins in warmer climates
• Spring: Tree pollen spreads north and often reaches its peak
• Late spring and summer: Grass pollen becomes the main problem
• Late summer and fall: Ragweed and other weed pollens take over
• After the first hard freeze: Outdoor pollen usually drops sharply
• Year-round: Indoor allergens like dust mites, pet dander and mold can still cause symptoms

When Does Allergy Season Start?

Allergy season can begin during winter in parts of the South, Southwest and West Coast where freezing temperatures are less common.

Trees such as cedar, juniper, alder and elm may begin releasing pollen during mild stretches. As temperatures warm, tree pollen season gradually spreads north.

By early to mid-spring, tree pollen is often the main outdoor allergen across much of the country.

The exact start changes from year to year. A warm end to winter can bring an earlier start, while a late freeze may slow things down.

Spring Allergy Season: Trees Take Over

Spring is often the first major allergy season of the year.

Tree pollen typically increases across the southern United States first before spreading into the Midwest, Northeast and other northern regions. Common triggers include oak, birch, maple, cedar, cottonwood and pine.

Pollen can travel on the wind, so you do not need to have a particular tree in your yard to feel the effects.

Tree pollen season generally winds down by early summer, although timing varies by climate and elevation.

Summer Allergy Season: Grass Joins the Party

As tree pollen fades, grass pollen usually takes its place.

Grass allergy season often begins during late spring in warmer parts of the country and continues through summer farther north. Common triggers include Bermuda, Timothy, Kentucky bluegrass, ryegrass and Johnson grass.

The hottest and driest parts of the Southwest may get a temporary break when extreme heat sends some grasses into dormancy. However, wind can still kick up dust and other particles that irritate the eyes, nose and lungs.

Fall Allergy Season: Ragweed Arrives

Ragweed is one of the most common fall allergy triggers.

Its pollen season generally begins during July or August and peaks during late summer or early fall. Ragweed grows across much of the United States, particularly in open fields, along roadsides and near disturbed soil.

Ragweed pollen is light enough to travel long distances, which means it can cause symptoms even where the plant is not immediately visible.

The season usually continues until the first hard frost damages the plants. Warmer fall temperatures and later freezes can keep ragweed producing pollen longer.

Does Allergy Season End During Winter?

Outdoor pollen levels usually reach their lowest point during winter across much of the country.

However, warmer areas may have only a short break before trees begin releasing pollen again. Some plants can also pollinate year-round in frost-free climates.

Winter does not guarantee relief from every allergy, either. Spending more time indoors can increase exposure to dust mites, pet dander and indoor mold.

If symptoms continue after outdoor pollen levels fall, an allergist may be able to help identify another trigger.

Which Season Is Worst for Allergies?

There is no universal worst season.

Spring may be miserable if tree pollen is your main trigger. Someone allergic to grasses may struggle more during late spring and summer, while ragweed can make late summer and fall the toughest stretch.

Your location matters, too. Allergy season generally begins earlier and lasts longer in warmer climates. Higher elevations and colder northern areas often start later, although their pollen levels can still climb quickly once spring arrives.

The amount and type of pollen in the air depend on both the season and geographic region. 

How Weather Changes Allergy Season

The calendar provides a general guide, but the weather decides how each season actually unfolds.

Warm temperatures can encourage plants to grow and release pollen earlier. Dry, windy weather can send more of that pollen into the air, while steady rain may temporarily wash it out.

Longer-term changes are also stretching the season in many places. Warmer temperatures, fewer frost days and rising carbon dioxide levels can affect when pollen season begins, how long it lasts and how much pollen plants produce.

Read more: Are Pollen Seasons Getting Worse?

You can also learn how daily weather can make your allergies worse

How to Prepare for Allergy Season

A few small changes can help reduce your exposure:

• Check the local pollen forecast before spending extended time outside
• Keep windows closed when pollen levels are high
• Shower and change clothes after outdoor activities
• Wash pollen from pets before they come inside
• Use an appropriate high-efficiency HVAC filter
• Speak with your healthcare provider if symptoms are worsening

Some allergy medications work best when started before symptoms become severe, so talk with your doctor about when to begin treatment.

Stay one step ahead of the next pollen spike by checking local pollen levels and weather conditions in the WeatherBug app.

Bottom Line

Allergy season does not have one national start or end date.

Tree pollen typically dominates spring, grass pollen becomes more common during late spring and summer, and ragweed takes over during late summer and fall. Where you live, what triggers your allergies and how the weather behaves will determine when symptoms are most likely to flare up.

The plants may follow the seasons, but your local pollen forecast will tell you when it is time to grab the tissues.