Cold Season Risk Index 2025 — Which States Are Most Likely to Catch a Cold This Winter

With colder weather approaching and coughs and sniffles starting to creep up across the U.S., we updated our seasonal risk model to estimate which states are most—and least—likely to catch a cold this season.

By combining factors like social activity, flu-shot rates, population density, search trends for cold symptoms, and demographics, The Action Network’s Cold Season Risk Index delivers odds — much like a betting slip — showing who’s more exposed and who’s safest this winter.

How the Index Works

We merged six publicly available metrics to score each U.S. state by relative risk:

• Avg. activity levels (movement and social behaviour)
• Search volume for cold/flu-related terms (proxy for illness spread and awareness)
• Vaccination / flu-shot rates (proxy for immunity)
• Population density (crowded places = easier spread)
• Median age (older populations tend to be more susceptible)

Each state’s data was normalized and combined into a single index value (roughly 20–72) — where a higher score signals a higher risk of catching a cold or flu this season. From there, we translated those scores into realistic seasonal odds: fractional, decimal, and American-style, giving readers an intuitive sense of risk.

Nationwide Cold Risk: Who’s Hot, Who’s Chilly

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Key takeaway: Living in D.C. this winter is roughly like flipping a coin — odds are you catch a cold. In Vermont? Odds are about 1 in 5.

High-Risk States (Watch Out)

• District of Columbia — Crowded, active, and urban, D.C. ranks highest. Its compressed urban environment and high mobility make it the top cold-risk state.
• Florida & New Mexico — Despite very different climates, both states show high activity and low immunity metrics. Florida’s high search volume for cold/flu terms suggests elevated spread or concern; New Mexico’s social behaviours and moderate vaccination rates also land it high on our risk list.
• New Jersey, Mississippi & South Carolina — All present a dangerous mix of density, moderate-to-low vaccination, and behaviour patterns that push them into the top five.

These states may want to start thinking early about flu shots, increased hygiene, and minimizing exposure — especially in public indoor spaces.

Low-Risk States (The Quiet Corners)

• Vermont, South Dakota, Minnesota, Montana, Alaska — Among these, Vermont has the lowest overall risk (odds ~5/1), thanks to low density, higher vaccination coverage, lower activity levels, and smaller seasonal-search volumes.
• Rural and lower-density states generally dominate the bottom of the risk ranking, proving that — for colds at least — breathing room and lower social exposure still help.

Full Ranking – All States including D.C.

Data notes: Search Volume and Activity Level are scaled index scores; Vaccination Rate is a percentage; Population Density is residents per square mile.

What This Means for the Average American

• Odds Are Not Guarantees: This model offers relative risk — not a medical guarantee. A “+500” doesn’t mean you won’t catch a cold; it just means your odds are considerably lower than states at the top of the list.
• Modifiable Risk: Many of the index’s drivers (social activity, vaccination rates, exposure) are things individuals can influence.
• Use the Data Proactively: If you live in a high-risk state, consider flu vaccination, limiting indoor gatherings, and stepping up hygiene. For low-risk states — don’t ignore it. Cold and flu viruses don’t respect odds entirely.

Winter is around the corner, and with it comes a familiar foe: the common cold (or worse). Thanks to our composite Cold Season Risk Index, you now have a clearer, state-by-state gauge of how exposed you are — and how to act accordingly.

Whether you’re betting on health or just staying smart, use the odds to shape your winter strategy.

Methodology

To create the Cold Season Risk Index, we combined five core data points for all 50 U.S. states plus Washington, D.C.:

• Flu activity levels (state-level weekly averages from 2021–present)
• Cold/flu–related Google search volume, adjusted per capita
• Vaccination rates (2023–24, USAFacts)
• Population density (Wikipedia)
• Median age (World Population Review)

Each metric was normalized to a 0–100 scale, then weighted to build a composite score:

• Flu activity (30%)
• Cold-related search volume (30%)
• Vaccination rate — inverted so lower vaccination = higher risk (20%)
• Population density (20%)
• Median age (10%)

These scores were combined into a final Risk Index, then ranked from highest (most risk) to lowest (least risk).

How We Turned the Risk Index Into Odds

To make the results easier to understand — and consistent with betting-style analysis — each state’s risk score was converted into realistic winter “odds of catching a cold.”

Here’s how:

1. We scaled each risk score proportionally into an implied probability range of roughly 45% (highest risk) to 16% (lowest risk), ensuring a realistic distribution without implying medical certainty.
2. Implied probabilities were then converted into:

• American odds (positive for lower risk, negative for highest risk)
• Fractional odds (rounded to the nearest whole-number ratio)

This creates state-by-state cold-season odds that can be compared just like betting markets — but strictly as a relative risk model, not a medical forecast.

You can find the full data set here.