Peak timing in the northern hemisphere: simulations and real data. Peak weeks of the epidemic activity in the baseline stochastic forecast output (SFO) (gray). The reference ranges of the simulated peak week were obtained by analysis of 2,000 stochastic realizations of the model for three different values of the seasonal rescaling factor, α
min, of 0.6, 0.65, and 0.7. The peak weeks reported by the surveillance for the fall/winter wave are shown as color gradients, whose limits correspond to the time interval at which an incidence of greater than 80% of the maximum incidence was observed. The numbers 1 to 5 indicate the type of data provided by the surveillance of each country, and the numbered weeks of the year correspond to the calendar used by the US Center for Disease Control and Prevention.