Pollen seasons across North America are lasting longer and producing more pollen, creating a tougher allergy season for millions of people.

Quick Breakdown

• Are pollen seasons getting worse? Yes. A major North American study found pollen seasons became about 20 days longer between 1990 and 2018.

• Is there more pollen now? The same study found pollen concentrations increased by about 21%.

• Why is pollen season getting longer? Warmer temperatures can extend the growing season and give plants more time to release pollen.

• Does carbon dioxide affect pollen? Higher carbon dioxide levels can encourage some plants, particularly ragweed, to grow faster and produce more pollen.

• What can allergy sufferers do? Check the daily pollen forecast, limit exposure on high-pollen days and talk with a doctor if symptoms are worsening.

Every year, pollen season seems to hit a little harder.

Your eyes itch when they may not have before. The yellow film on your car looks thicker than ever. Your allergy symptoms start earlier, linger longer and may feel more difficult to control.

So, is pollen season actually getting worse?

The short answer is yes. It is not just your imagination.

One major study analyzing pollen data from across North America found that pollen seasons became about 20 days longer between 1990 and 2018, while pollen concentrations increased by approximately 21%.

Why Are Pollen Seasons Getting Longer?

Warmer temperatures give many plants more time to grow and release pollen.

When winter ends earlier and the first freeze arrives later, the growing season can stretch across more of the calendar. Trees may begin releasing pollen sooner in the spring, while grasses and weeds can remain active later into the year.

That can turn what once felt like a few difficult weeks into months of recurring allergy symptoms.

Why Can More Carbon Dioxide Mean More Pollen?

Carbon dioxide is one of the ingredients plants use to grow.

As carbon dioxide levels rise, some plants can grow faster, become larger and produce more pollen. Ragweed is one of the clearest examples studied by scientists.

This means allergy season can change in two ways at once: plants may release pollen for a longer period, and some may produce more pollen while they are active.

When Is Pollen Season?

Pollen season depends on the plants growing near you, but it generally follows this pattern:

• Tree pollen: Most common during late winter and spring

• Grass pollen: Often highest during late spring and summer

• Weed pollen: Usually strongest from late summer into fall

• Ragweed pollen: Common during late summer and fall, often continuing until the first hard freeze

These seasons can overlap. That means some people move from tree pollen directly into grass and weed pollen with very little relief in between.

Local weather also makes a difference. Warm, dry and windy days can send more pollen into the air, while rain may temporarily wash pollen out of the atmosphere.

Why Do Your Allergies Feel Worse Now?

Longer seasons and higher pollen levels can increase the amount of time your body is exposed to allergens.

People who are already sensitive to pollen may notice symptoms beginning earlier, becoming more intense or lasting later into the year. Those with asthma may also experience worsening symptoms when pollen levels are high.

Common pollen allergy symptoms include:

• Itchy or watery eyes

• Sneezing

• Runny or stuffy nose

• Scratchy throat

• Coughing

• Fatigue

• Worsening asthma symptoms

Pollen may not be the only factor. Mold, air pollution, smoke and changing weather conditions can also contribute to symptoms.

Why Does Your Allergy Medicine Feel Less Effective?

If your usual allergy medicine does not seem to be working as well, it does not necessarily mean the medication suddenly stopped working.

You may be exposed to higher pollen levels or dealing with symptoms for a longer stretch of time. Some allergy medications also work better when taken consistently or before exposure rather than after symptoms become severe.

However, worsening symptoms can have several causes. Do not increase your dosage or combine medications without checking with a doctor or pharmacist.

If your allergies are disrupting sleep, affecting daily life or making asthma harder to control, it may be time to discuss other treatment options with a healthcare professional.

How Can You Reduce Pollen Exposure?

You cannot avoid pollen completely, but a few small changes may help:

• Check the pollen forecast before spending extended time outside.

• Keep windows closed when pollen levels are high.

• Change clothes and shower after being outdoors.

• Avoid leaving outdoor clothing on beds or furniture.

• Wipe down pets that have spent time outside.

• Use air conditioning and replace filters as recommended.

• Plan outdoor activities for times when local pollen levels are lower.

Before heading outside, check your local pollen forecast with WeatherBug so you know what is in the air and can plan around the highest levels.

The Bottom Line

Pollen season really is changing.

Warmer temperatures are helping extend the growing season, while rising carbon dioxide levels can encourage some plants to produce more pollen. Together, those changes can make seasonal allergies begin earlier, feel more intense and linger longer.

So, if pollen season seems harder than it used to be, you are not alone.

If your symptoms are getting worse, your regular medications are no longer providing enough relief or pollen is aggravating your asthma, talk with your doctor.

Sources: Proceedings of the National Academy of Sciences, U.S. Environmental Protection Agency and National Institute of Environmental Health Sciences.