Flu season is the time of year when cases of influenza (the flu) increase significantly in communities. Although many people associate the flu with the coldest winter months, the reality is more nuanced. The start, peak, and duration of flu activity can shift from year to year rather than following a fixed calendar.
The timing of flu season varies based on factors like geographic location, circulating virus strains, and population behavior, which can make it difficult to know when your risk is highest. Understanding when flu activity typically begins, reaches its peak, and tapers off can help you take proactive steps to protect yourself and your family.
This guide breaks down what to expect during flu season months, what influences the timing, and how to prepare.
Understanding Flu Season and Seasonal Patterns
Influenza is a contagious respiratory illness caused by flu viruses that affect the nose, throat, and sometimes the lungs. While flu viruses circulate year-round, cases tend to rise sharply during certain months—this pattern is what we refer to as flu season.
There is an important distinction between:
- Year-round flu cases: A small number of cases can occur in any month.
- Seasonal surges: A predictable spike in cases that happens during colder months in most parts of the United States.
These seasonal increases are influenced by environmental factors, human behavior, and changes in immune defenses.
When Does Flu Season Start?
Many people are surprised to learn that flu season can begin earlier than expected. In most years, flu activity in the U.S. starts to increase in early fall, often around October.¹
There is a difference between early circulation and the official start of flu season. Even before case numbers rise significantly, the virus may already be spreading quietly within communities. Schools reopening, increased indoor gatherings, and seasonal travel all contribute to earlier transmission.
Dr. Yelena Kopyltsova notes: “Many people don’t realize that flu season can start in the fall, as early as October and last into the spring, not just during the winter months.”
This is why healthcare providers emphasize getting vaccinated and preparing before winter arrives.
When Is Peak Flu Season?
Peak flu season is the time when flu cases reach their highest levels. In the United States, this most often occurs between December and February, though some seasons peak as late as March.¹
Several factors likely contribute to higher transmission during winter:
- Indoor crowding: People spend more time indoors, in close contact with others.
- Lower humidity: Dry air can allow respiratory viruses to survive longer.
- Weakened immune defenses: Less sunlight exposure and seasonal changes can affect immune response.
It’s important to remember that peak flu season can shift from year to year. Some years bring earlier surges, while others see prolonged activity into the spring.
When Does Flu Season End?
Flu season typically begins to taper off in late spring, usually around April or May. However, a decline in cases does not mean the risk disappears overnight.¹
Late-season flu cases can still affect vulnerable populations such as:²
- Older adults
- Young children
- Pregnant individuals
- People with chronic conditions
As Dr. Kopyltsova explains: “You can still catch the flu even when it feels like the season is ‘winding down.’”
Staying vigilant through the end of the season remains important, especially for higher-risk individuals.
How Long Does Flu Season Last?
In the U.S., flu season often spans six to eight months, generally from October through April or May.¹ Some seasons feel longer than others due to:
- A higher number of circulating flu strains
- Overlap with other respiratory illnesses (like RSV and COVID-19)
- Regional outbreaks extending activity later into the year
Understanding this extended window helps people avoid letting their guard down too soon.
Does Flu Season Vary by Year or Location?
Yes—flu season is not identical every year or in every place.
Year-to-year variation happens due to:
- Changes in dominant flu strains
- Differences in vaccination rates
- Public health factors and population behavior
Regional differences also matter:
- Colder regions often experience sharper winter peaks.
- Warmer climates may see more prolonged or less predictable flu activity.
In the southern U.S., flu activity can sometimes extend later into the year, while northern states may see earlier winter peaks. Globally, flu season differs by hemisphere, when it’s flu season in North America, it’s often the off-season in countries south of the equator.
Can You Get the Flu Outside of Flu Season?
Yes—you can still get the flu outside of traditional flu season months. While the risk is lower in summer, it is not zero. Sporadic cases and localized outbreaks do occur year-round.
This is why recognizing flu symptoms and seeking appropriate care matters even outside the typical season.
If you’re experiencing persistent cold or flu symptoms, ENT-focused care may be beneficial.
When Should You Get a Flu Shot?
The best time to get a flu shot is before flu season starts, ideally by late September or October. Early vaccination allows your body time to build immunity before flu activity increases.
That said, getting vaccinated later is still beneficial. If you miss early fall, it’s not too late to get your flu shot in winter or even early spring.
Dr. Kopyltsova addresses a common concern: “One of the biggest myths is that the flu vaccine can give you the flu. Extensive research has shown this isn’t true—the vaccine cannot cause influenza and helps reduce how sick you may become if you’re exposed.”
She also highlights broader health risks: “The flu can make existing conditions like asthma or allergies worse and may trigger more serious complications. Studies also show that influenza can increase the risk of heart problems, especially in older adults.”
How to Protect Yourself During Flu Season
Beyond vaccination, daily habits play a major role in reducing your risk.
Effective flu prevention strategies include:
- Frequent handwashing with soap and water
- Avoiding close contact with people who are sick
- Staying home when you feel unwell
- Cleaning commonly touched surfaces
- Wearing a mask in high-risk or crowded settings (optional but helpful)
Why Flu Season Awareness Matters
The flu is often underestimated, but it can lead to:
- Missed work and school
- Serious complications like pneumonia
- Hospitalization, especially in high-risk individuals
Awareness allows you to:
- Get vaccinated on time
- Recognize symptoms early
- Seek appropriate medical care
- Protect vulnerable family members and community members
Preparation is one of the most powerful tools in reducing the impact of influenza season.
Other Frequently Asked Questions
What months are considered flu season?
Flu season months in the U.S. generally range from October through April or May, with the highest activity often occurring between December and February.¹
Is flu season the same every year?
No. The timing and severity of flu season vary depending on circulating strains, vaccination rates, and public health factors.
Can children and adults have different flu season risks?
Yes. Children, older adults, and individuals with chronic conditions often face higher risks of complications and should take extra precautions.
When is it too late to get a flu shot?
It’s rarely “too late.” As long as flu viruses are circulating, vaccination can still offer protection.
How do I know if I have the flu or a cold?
The flu often causes more intense symptoms such as high fever, body aches, fatigue, and chills. A medical evaluation can help determine the difference.
When to Seek Medical Care for the Flu
Many flu cases can be managed at home with rest and hydration, but certain symptoms should never be ignored.
You should seek medical care if you experience:²
- Persistent or high fever
- Difficulty breathing
- Chest discomfort
- Severe fatigue or weakness
- Confusion
- Symptoms that improve and then suddenly worsen
ENT-related symptoms such as significant sinus pressure, ear pain, ongoing sore throat, or nasal congestion that does not improve may also benefit from specialized evaluation.
Dr. Kopyltsova explains: “One of the most common complications of a flu infection is pneumonia (infection of your lungs). You should seek medical care if you have trouble breathing, chest pain, a high or persistent fever, severe weakness, confusion, or symptoms that improve and then suddenly worsen. Young children, older adults, pregnant individuals, and those with chronic conditions that can compromise your immune system should seek care earlier.”
Care Backed by Experience and Specialized Expertise
Cold and flu symptoms often affect the ears, nose, throat, and breathing—areas where ENT-level expertise can make a meaningful difference. ENT & Allergy Associates specializes in diagnosing and treating upper respiratory conditions related to flu, sinus infections, throat concerns, and ear involvement, with a focus on personalized, symptom-specific care rather than one-size-fits-all treatment.
With convenient locations throughout New Jersey, New York, Pennsylvania, and Texas, patients have access to specialized care in both urban and suburban communities. During flu season and beyond, expert support can help you recover more comfortably and confidently. Booking an appointment online makes it easy to get care when you need it.
Sources:
CDC. Flu Season.
- CDC. Signs and Symptoms of Flu.