Seasonal Childhood Illnesses
A month-by-month guide to typical Midwest seasonal patterns for RSV, flu, COVID-19, stomach bugs, allergies, and other illnesses affecting children.
The early warning layer for pediatric illness
This guide is a qualitative baseline, adjusted for Chicago and the Midwest. Bubble size shows typical relative seasonal activity, not measured case rates or a forecast. Actual timing changes with weather, school calendars, circulating strains, and local outbreaks.
How to read the chart
These shapes compare each illness with its own typical year. They do not compare how common one illness is with another.
Typical Oct patterns
Strongest seasonal signals in Oct
Rising into Nov
Early warning signs to watch for
Seasonally elevated in OctThese are common early signs, not a diagnosis. Call your pediatrician if symptoms worsen or you are unsure.
Some childhood illnesses follow predictable seasonal patterns, while others vary substantially. Below is a Chicago-focused guide to ten common conditions seen around schools, daycares, and homes.
December through February, with cases rising in October and tapering by April.
Sudden high fever (often over 101 F), body aches, chills, dry cough, sore throat, and unusual fatigue.
All ages, but young children, kids with asthma, and those under 5 are at higher risk of complications.
Usually rises in October, peaks in winter, and can remain active into March or April.
Runny nose, congestion, wheezing or fast breathing, persistent wet cough, and poor feeding in babies.
Infants and children under 2 are most vulnerable to severe RSV. Most older kids experience it as a bad cold.
Summer and winter waves can occur, but neither is guaranteed and timing differs by year.
Fever or chills, cough, sore throat, runny nose, congestion, and fatigue.
Children of all ages can be infected. Risk of severe illness varies with age and underlying conditions.
Year-round, but worse September through April when kids are indoors together.
Runny or stuffy nose, sneezing, mild cough, scratchy throat, and a low-grade fever.
Preschool and elementary-age kids average 6 to 10 colds per year. Daycare-age kids can get more.
The school year, with the biggest spikes in late winter and early spring.
Sudden sore throat without a cough, painful swallowing, fever over 100.4 F, swollen neck glands, and white patches on the tonsils.
Kids ages 5 to 15. Strep is uncommon in children under 3.
November through April for norovirus, with year-round daycare outbreaks.
Sudden vomiting, watery diarrhea, stomach cramps, and a low-grade fever or chills.
All ages, but dehydration is the biggest concern for babies and toddlers.
Summer and early fall, June through September.
Mild fever and fussiness, painful mouth sores, red spots or blisters on hands and feet, drooling, or refusing to eat.
Children under 5, especially in daycares and summer camps.
No single reliable peak. Viral, bacterial, and allergic conjunctivitis follow different patterns.
Red or pink eye whites, itchy or gritty feeling, watery or yellow discharge, and crusty lashes after sleep.
Preschool and elementary kids, where it spreads quickly through shared toys and contact.
Chicago typically sees a spring tree and grass pollen peak, then a late-summer and fall ragweed peak.
Sneezing fits, itchy or watery eyes, clear runny nose, and no fever (which helps distinguish allergies from a cold).
Kids 3 and older. Many children develop seasonal allergies in early elementary years.
Back-to-school weeks (August through October) and again after winter break.
Persistent scalp itching, a tickling feeling in the hair, tiny white eggs (nits) near the scalp, and red bumps on the neck or behind the ears.
Elementary-age children, most often ages 3 to 11.
These are typical seasonal trends, not measured monthly infection rates. Actual illnesses circulating in your neighborhood can vary considerably from year to year. Flu and RSV have stronger surveillance-based patterns. COVID-19, pink eye, common colds, lice, and local outbreaks are less predictable.
Ten conditions. Twelve months. One baseline, with local reports showing what is happening now.
