Seasonal cycles

A seasonal cycle is a repetitive, predictable pattern in the series values.

Seasonal cycles are tied to the interval of your series. For instance, monthly data typically cycles over quarters and years. A monthly series might show a significant quarterly cycle with a low in the first quarter or a yearly cycle with a peak every December. Series that show a seasonal cycle are said to exhibit seasonality.

Seasonal patterns are useful in obtaining good fits and forecasts, and there are exponential smoothing and ARIMA models that capture seasonality.