We have published this post in mid-May, which seems like the time people would start indulging in ice cream. It’s not quite “I scream for ice cream” time, but the days are getting sufficiently warm to warrant stocking up cool treats. And ice cream is the quintessential seasonal product that is only in demand when it’s hot out. Right? Just look at the FRED graph for ice cream production: A classic example of seasonality! But wait… These data are very old. How does it look if we use current data?

The FRED graph below shows ice cream production since 1972 (in red). Yes, it is still seasonal, but it less so than in the early years or even a dozen years ago. It’s also striking that ice cream production now is barely higher than it was 50 years ago, despite roughly 60% more population. We added the price of ice cream to our second graph, and here we notice no seasonality at all. One would have expected some, as demand visibly fluctuates through much of the year and production costs may as well.

Keeping ice cream cold in the summer is more challenging, but research shows that ice cream prices do not vary with outside temperature, as manufacturers cannot amend prices quickly enough to adjust to short-term demand fluctuations. It seems this is also true for even predictable seasonal changes.

How these graphs were created: Search FRED for “ice cream,” select the historical production series, and you have the first graph. For the second graph, from the same search result, take the current production series, click on “Edit Graph,” open the “Add Line” tab, search again for “ice cream,” take the price series, open the “Format” tab, and put the legend for one of the series on the right.

Suggested by Christian Zimmermann.