Fluctuations in demand for products / services in relation to the seasons of the year. This will mean that cash from sales does not flow in evenly over the year and that there may be periods of cash shortage and cash surplus. In a successful business that is coping with seasonality, the surplus in the peak will tide them over during the off peak period. In a struggling business, the cash surplus during the peak period might be insufficient to tide them over during the lean period.