A seasonal forecast looks to the same months in prior years as the sales reference period.

This approach is beneficial for holiday and seasonally-driven items with more than 12 months of history. Sales velocity is not considered, but a trend is applied by evaluating sales over the last 12 months vs the prior 12 months.

For example, sales from January 2018 and January 2019 impact the forecasted needs for January 2020. If today is December 31, 2019, the trend will be based on sales between January and December 2019 vs January and December 2018.

When an item has fewer than 12 months of sales history, the seasonal forecasting method computes a seasonal forecast at the category level, then distributes forecasted sales to individual variants.

For items with fewer than 12 months of sales history, the last 3 months of sales are used to determine each variant's contribution to the total unit sales of the category. Non-replenishable and non-tracked products are excluded from this distribution.

For example, if Variant A contributed 5% of the sales units to Category Z during the period, then Variant A will receive 5% of the category's forecasted sales in upcoming months.

Enabling seasonality

There are three methods to set variants to use a seasonal forecast:

Account-wide as the default forecasting method
Using bulk actions to apply seasonal forecasting to a group of variants
One variant at a time using the Details dialog

Setting seasonal forecasting as the account-wide default

To set seasonal forecasting as the default method used to calculate customer demand, go to Account > Settings > Forecast, and set the "Default forecasting method" to "Seasonal".

Note: It's best to use this approach when all or most variants are seasonal. If a minority of variants in your store are not seasonal, then disable seasonality only for those variants using one of the methods below (by assigning them a non-seasonal forecasting method).

Applying seasonal forecasting in bulk to a group of variants

To apply seasonal forecasting to a group of variants, go to Replenishment and select the relevant variants using the checkboxes on the left-hand side.

Click Bulk actions > Set forecast settings.

On the resulting popup, enable "Use custom forecast settings", then choose "Seasonal" from the forecasting method dropdown options.