Absolutely there are weather-related trends in retail. But, weather is just one data point that retailers take into their calculations.
Most major retailers actually have forecasting software (as in demand-forecast, not a weather forecast per se) that takes multiple factors such as year-on-year sales history, trends and other data points—including weather—to determine how much stock on hand they’ll need per each store location.
The classic example that is the case in point for algorithms behind this sort of demand forecasting software is this scenario:
Say you’re a big-box or grocery retailer and trying to determine how much bottled water to keep on the store shelves. Let’s say you’re basing your merchandise orders based on sales from last year at this time.
Well, if you only order what you sold last year, how do you know if you’ve missed selling more? Or, what if last year you sold more than you will this year because of a major weather event? For example: if you’re basing your orders only on sales history and you see a giant spike in water sales last Aug 20, 2011 (in advance of Hurricane Irene making landfall on the eastern seaboard of the US) you might over purchase water in August 2012.
What you need instead is a weather/NOAA feed with predictions for the upcoming Hurricane season, a smoothing of the sales from last year excluding the hurricane and yet representing what you could have sold if you had unconstrained inventory in the event that there is another predicted Hurricane this August.
In addition to demand forecasting there are trends (and as @JLeslie points out it depends very much on the type of retailer & the location/market segment in the US) across the entire economy – and lots of articles and science (and even companies focused on serving retailers!) on this topic.
A few more things I know retailers look at:
- Grocery retailers pay attention to dates when Food Stamps/electronic benefit transfer (EBT) card are reloaded each month. As you can imagine, higher traffic days in the grocery are connected to when people have newly added funds available. This date (or dates) varies State by State – -so think about how complex it is to be a retailer in multiple states! For example, in MN it might be on the 30th of the month, but in ME each month food stamp benefits are deposited onto an between the 10th and 14th and your deposit date depends on the recipient’s birth date.
- Many states pass temporary “Tax Vacation” sales dates. A common time of year for this is Back to School and this year 17 States have jumped on the bandwagon. (Article here)
So, retailers have to prepare MONTHS in advance for this an make sure they’ll have sufficient inventory on-hand for greater sales volumes of certain items during those dates.
- Holidays. Not just “Black Friday” or Christmas..but Fourth of July and Memorial Day, too. Retailers know you’re looking to buy a new TV before the Super Bowl in early January (and they also know who is likely to try and return it right after, too!)—they keep all kinds of metrics on what we buy and when.