When Does Flu Season Start, and When Does It End?

For many people, “flu season” and “winter” are basically the same thing. But flu season can last for over half the year — and its timing varies depending on where you live.

It’s possible to get the flu (influenza) at any time of year. You can even get the flu in the summer. But it helps to pay attention to the flu season. For one thing, you’ll know what to expect if you get sick. And it can help you plan ahead, so you can be sure to get a flu shot in time to avoid catching it. 

When is flu season?

In the U.S., flu season typically starts in October and continues into May. The busiest time for the flu is known as peak flu season. And its timing can vary. 

What months are flu season? 

In past years, peak flu season has typically been in mid-winter: December, January, February, or March. But flu season has become less predictable since the COVID-19 pandemic.

The 2021-2022 flu season began in November and lasted through June. There were two peak seasons: one in mid-December and one in mid-April. The second peak was much later than usual.

The 2022-2023 flu season saw infection rates return to levels that were common before the COVID pandemic. The peak occurred in late November and early December, which is a bit earlier than usual.

Researchers are still studying the 2023-2024 flu season. But the peak seemed to be in mid to late December.

Do cold and flu seasons typically occur at the same time?

Yes, although you can get either a cold or the flu at any time of the year. But in general, the winter months are most often associated with both cold and flu seasons — as well as seasons for other respiratory infections like RSV.

One thing to keep in mind is that only two viruses cause the flu in humans: influenza A and influenza B. The common cold, on the other hand, can be caused by over 200 different types of viruses. This helps explain why people get colds more often than they get the flu. And there’s no vaccine for the common cold. On average, adults get two to four colds a year. But only 8% of people in the U.S. get the flu every year.

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Does flu season change from year to year?

The flu season remains fairly constant from year to year, although the peak often changes. It’s also difficult to know how the flu will affect different parts of the country. Some areas can have large outbreaks in one week while other parts of the country have very few cases during the same week. 

Different reporting systems track weekly flu outbreaks during each season. Researchers use this information to predict when peak flu activity will occur in different parts of the country.

Tracking the timing of flu season is one thing. But it’s a different thing to predict how severe a flu season will be. This is called the “flu burden.” For example, the 2020-2021 flu season was 8 months long. But there were fewer cases reported during those months than in prior years. There were also fewer hospitalizations and deaths than in prior years. 

It’s likely that COVID-related precautions, along with record-high flu vaccine rates, played a role in keeping flu burden low that year. But flu numbers increased over the next 2 seasons. By the 2022-2023 flu season, the flu burden was similar to what it had been in the years before the pandemic. 

How is the flu season monitored?

There are state, national, and international surveillance systems that track flu virus activity. To calculate flu activity, the CDC provides national surveillance and tracks the following items:

• Data from clinical labs: Labs report the number of positive flu tests. 

• Data from outpatient visits: Healthcare professionals can volunteer to be part of ILINet, which provides data on how many people come to the office with flu-like symptoms.

• Data from hospitalizations: Some hospitals take part in FluSurv-NET, which provides data on how many people are hospitalized with the flu. 

The CDC’s FluView reports comprehensive flu activity data each week. They also have an interactive map where you can track flu activity throughout the country and see how the current flu season compares with previous years.

How can you protect yourself from the flu?

Here’s how to protect yourself from getting the flu:

• Avoid people who are sick with flu-like symptoms.

• Stay home if you have flu-like symptoms to avoid getting others sick.

• Wash your hands often with soap and water.

• Cover your nose and mouth when you cough or sneeze.

• Avoid touching your face, eyes, and mouth.

• Regularly clean and disinfect commonly used surfaces.

All of these strategies will help. But getting the flu vaccine is the best way to protect yourself from the flu and its complications. The flu vaccine is safe and effective for most people. Talk with a healthcare professional about getting the flu vaccine before the flu season begins.

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Written by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

Edited by:

Alex Eastman, PhD, RN

Alex Eastman, PhD, RN, is a California-based registered nurse and staff medical editor at GoodRx, where he focuses on clinical updates and Latino health.

Reviewed by:

Kerry R. McGee, MD, FAAP

Kerry McGee, MD, FAAP, has over a decade of experience caring for babies, children, and teenagers as a primary care pediatrician. She has a special interest in adolescent health, particularly in adolescent mental health.

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