How close is the flu season where you are? Type a US zip code or a city, or a city ex-US. FluPulse will generate a forecast based on public surveillance data where available.
FluPulse score, 0 to 100: county marked from above the bar, state from below. The figures in brackets and the short bar under each marker are the 80 percent range of the estimate, where the middle eight of every ten model refits fall.
On iPhone: tap Share, then "Add to Home Screen". On Android: open the browser menu, then "Add to Home screen". FluPulse then opens like an app.
One dot per county, colored by this week's band; grey dots have no score this week. Tap a dot to open that county.
The same model, run on RSV surveillance: emergency department visits for RSV, laboratory positivity, wastewater and hospital admissions, county by county.
In validation. The score appears here once it has been checked against past seasons the way the flu score was.
COVID does not keep to one season; it comes in waves, summer and winter. The score here will estimate how close the next wave is where you are, from emergency department visits, laboratory positivity, wastewater and hospital admissions.
In design. The score appears here once the wave definition is set and validated.
FluPulse is an estimate built from public surveillance data. It is not medical advice, not a diagnosis, and not a substitute for a clinician. The score says how likely flu season is to be under way in an area within four weeks; it says nothing about any one person's risk or illness. If you have symptoms, contact a clinician; in an emergency, call your local emergency number. FluPulse is not affiliated with the CDC, any state or national health department, or any test or vaccine maker; the guidance shown follows public CDC recommendations. Data are published with a lag and revised by their sources, and FluPulse is provided without warranty of any kind.
The same models used to forecast the emergence of these respiratory viruses can be used to inform and support the seasonality of the work your organization performs. These are examples of how your organization might benefit from our services.
All profits from FluPulse services are donated to charity.
Explore servicesLast updated September 15, 2026.
The FluPulse score is the probability, from 0 to 100 percent, that flu season begins in your area within the next four weeks. A score of 20 means a 20 percent chance; in the seasons we tested, places given that score went on to have flu season within four weeks about 20 times in 100, which is what makes the number a probability rather than a guess. Green is 0 to 24, amber 25 to 69, red 70 to 100.
As the season approaches, the card adds an onset window: the span of weeks, counted from today, within which flu season begins with 80 percent probability, for example “between 2 and 5 weeks from now”. The window comes from the same model fitted at each horizon from this week to twenty weeks out, and it is shown only when it is four weeks wide or narrower, since a wide window says little. It is set so that the statement holds: in the three replayed seasons, the season began inside a shown window 84 times in 100. Windows that narrow appeared in about one pre-season week in five, all of them close to onset; the rest of the time the four-week score is the forecast.
“Flu season begins” has a fixed, local meaning: the week a place’s own flu curve rises to a set fraction of what will be its seasonal peak, and it ends when the curve has fallen well below the peak for two weeks. A county’s season starts when its own emergency-department curve reaches that point, not when the national curve does.
Every day, for every US county, the score is computed from public surveillance published by the CDC and others:
Each input is read against the place’s own history, so that the same level of flu activity means more in a county that is normally quiet than in one that always runs high. Where an input is not published for a place that week, the score is computed by a version of the model built without it.
For cities outside the United States the inputs are the country’s weekly laboratory positivity and, where published, its consultation rate for influenza-like illness, from WHO FluNet and national health agencies; see “Other countries” below.
The score is a statistical model fitted to three past seasons of CDC county data, 2022-23 to 2024-25, for 70 locations across 24 states: 210 location-seasons and 9,030 location-weeks, each week scored only with the data that had been published by that week. A separate state score was built the same way on eight seasons of state data, 2016-17 to 2024-25 (2020-21 excluded, when there was no flu season).
Every result below is out of sample: each season was scored by a model that had never seen that season. The model is refitted repeatedly on resampled sets of locations to produce the ± shown next to every score, which is one standard deviation of the estimate.
County score, three seasons, all weeks. AUC 0.978. The AUC is the probability that, given one week that was followed by flu season within four weeks and one that was not, the score ranks the first above the second; 1.0 is perfect separation and 0.5 is a coin toss. The comparator throughout is the earlier three-band rule, which set the color from fixed thresholds on the same inputs; its AUC on the same weeks was 0.878. The Brier score, which measures how close the probabilities are to what happened, was 0.052 against 0.103 for the rule (lower is better). Per season, score against rule: 2022-23 AUC 0.989 against 0.916, Brier 0.053 against 0.077; 2023-24 AUC 0.989 against 0.879, Brier 0.042 against 0.106; 2024-25 AUC 0.970 against 0.854, Brier 0.061 against 0.125.
The harder test: weeks before onset only. Once a season is under way the score is easy; the question that matters is whether it warns in advance of onset. On the 3,933 weeks before local onset, the AUC of the score was 0.945 and the AUC of the earlier rule was 0.898: the score ranked a pre-onset week that led to a season above one that did not 94.5 times in 100, the rule 89.8 times.
Calibration. When the score says 20 to 30, the season followed 29 percent of the time; 40 to 50, 48 percent; 60 to 70, 69 percent; 80 to 90, 80 percent; 90 to 100, 98 percent. Across the eleven bins the predicted and observed rates are within a few points of each other.
Bands. In the replay, green weeks (0 to 24) were followed by the season within four weeks 4 percent of the time, amber weeks (25 to 69) 46 percent, red weeks (70 to 100) 95 percent. The first week a place crossed 25 came a median of five weeks before its season began; the first week above 70, three weeks before.
State score, eight seasons, 24 states. AUC 0.959 on all weeks and 0.916 before onset; the earlier rule 0.838 and 0.810. The gain held in every one of the eight seasons.
Other countries. For places outside the United States the state score is applied to each country’s national laboratory positivity from WHO FluNet, 2014 to 2025, and then recalibrated on that country’s own history. The transferred score ranks weeks well but its probabilities run too high; recalibration fixes that. Six countries pass the test (Denmark, Norway, France, Germany, Italy, China; recalibrated AUC before onset 0.81 to 0.98). Four do not (Singapore and Thailand, where flu runs year round; the Netherlands and Switzerland, on too few usable seasons) and carry a “not validated” label. Japan, Finland, Taiwan and Canada could not be tested.
CDC NSSP emergency department visits; CDC NREVSS clinical laboratory positivity; CDC ILINet outpatient visits; CDC NWSS wastewater; NOAA and Open-Meteo temperatures; Washington State Department of Health; NYC Department of Health; WHO FluNet for countries outside the United States. FluPulse is not affiliated with any of them.