Imagine if we could forecast influenza or “the flu”, just like the weather. Researchers at Columbia University recently made a “flu forecast” website to do that. Their website shows you the number of people who had the flu in your city or state this week, and predicts when the influenza season will reach its peak in selected cities.

Here are some definitions to help you understand the flu forecast website:

ILI+ means influenza-like illness. This diagnosis is used when people have symptoms of the flu, but it has not been confirmed by testing that they have the flu virus.

AH-3 and B are the names of the two types of flu virus common this year. Unlike the ILI+ graphs, these graphs represent people who have been confirmed to have the flu virus.