Unpredictable weather patterns - frosty springs, mild winters and wet summers - are posing a challenge for fashion designers.

As our climate becomes more changeable, the fashion industry is struggling to create clothes we'll want to wear in a year's time, with no idea what the weather will be like when their collections hit the shelves.

And when they get it wrong, the clothes simply stay in the shops until they end up being heavily discounted, which hurts sales.

Some designers have resorted to creating largely seasonless clothing. “Because of the extreme weather changes, there’s no real separation between spring, fall, winter and summer,” designer Jason Wu told the Wall Street Journal.

But some of the biggest retailers have started hiring climatologists to help them predict what the seasons might have in store. The Fashion Institute of Technology in New York has even launched a new course called “Predictive Analytics for Planning and Forecasting: Case Studies with Weatherization.”

In fact, the FIT - whose alumni include Calvin Klein and Brian Atwood - as a whole is being overhauled to include more topical issues including weather.

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The new course is designed to appeal to students with an interest in retail and merchandising, and it’s hoped will help the fashion industry deal with the impact of climate change.

Students embarking on the course need to be prepared to get technical - graphs, spreadsheets and equations feature heavily.

One class was asked "When should a Los Angeles store stock swimsuits?" and whoever answered correctly was promised a Dunkin' Donuts voucher. The winner was sernior student Sarah Corcoran, who knew to use a "maximum temperature metric".

Students are also given challenges like incorporating weather data into calculations to work out when a shop in Chicago should sell more fleece.

The course is divided into statistics, taught by maths professor Calvin Williamson, and merchandising and marketing, taught by Gary Wolf, who is assistant professor of fashion business management.

One student on the course explained that she’s realised how important it is not to rely on what the weather was like the previous year: “It can make you one step ahead of a competitor who is just looking at what happened last winter.” said Melissa Weilacher, a senior majoring in international fashion business management.