In fact, so sensitive is the British shopper to changes in temperature that even a degree or two either way can increase sales of some lines by as much as 400% over a short period.
It's not hard to figure out why people buy more ice cream, beer, salad and leg wax when it's hot, but the extent to which sales can leap means that some businesses are waking up to what a powerful strategic tool weather information can be.
A recent survey, undertaken by Datamonitor for the Met Office, reveals that in the UK grocery and clothing sectors alone, integrating weather-forecast information into business planning could boost sales by £4.5bn per year. The figures refer to the opportunity that could be realised if weather-forecast data was used to help retailers maximise revenue per square foot (see table). This 'opportunity' is worth 5% of total grocery sales (£3bn) and nearly 6% of clothing sales (£1.5bn).
The research, which was compiled with the co-operation of retailers including Sainsbury's, Asda, Safeway, Debenhams, Monsoon and Bhs, shows the potential profits, and losses, to be made from the weather. For example, it reveals how Safeway used a Met Office prediction that the days before Easter this year were going to be particularly hot, to adjust its weather-sensitive stock levels and tailor its in-store promotions. The result was a £2m uplift in sales. A buy-one-get-one-free promotion for Haagen-Daz ice cream, planned to coincide with the hot weather, saw the retailer sell as much in one week as it normally achieves in an entire year.
And the consequences of poor planning are costly. One supermarket chain that failed to match stock planning with the forecasted weather suffered an estimated £1m loss in a single week. Another saw a tripling of its wastage levels on a product line to £250,000 over one weekend.
One conclusion made by the report is that clothing retailers make little use of weather information in their strategic planning, showing more concern with other variables, such as when people are paid, bank holidays, and, of course, fashion trends. Alex Solomon, an analyst with Datamonitor and author of the 'Profiting from Weather Information' report, says clothing chains "seem to have the attitude that the weather doesn't affect them, but they are losing out by not paying closer attention. I'm not suggesting they should change their store layouts at the first sign of sun, just try to become more flexible. I think a lot of fashion retailers - and this goes for many other areas of business - have become used to blaming unseasonal weather for poor sales, but as forecasting technology improves, it's less of an excuse."
Jonathan Hearth, marketing director for the Met Office, confirms that large improvements in the accuracy of weather forecasting technology have been made. This is the result of a big investment in R&D by the government following Michael Fish's notorious 'what hurricane?' blunder of 1987.
The increase in accuracy is supposedly marked, with Hearth saying: "Our ability to predict has improved to the extent that we can now be as accurate three days in advance as we could only 24 hours ahead 20 years ago."
Clearly, the appointment of Hearth last year as the Met Office's first ever marketing director shows the government agency is keen to sell more of its services to business. Commercial customers already bring in a healthy revenue - £21.5m according to the Met Office's 2001/2002 annual report - some 14% of its total income.
Hearth says the power-generation sector is another big user of its business-focused weather services, as surges in demand for power are closely linked to sudden changes in weather conditions (air conditioning in summer, heat in winter).
The Met Office typically provides its business customers with a 30-day 'trend' report, giving a broad forecast that can then be firmed up with a ten-day detailed weather report. Hearth says the large supermarket chains are shining examples of how weather data can be harnessed for business gain, often able to change their plans as little as 24 hours in advance.
Many combine current weather forecasts with historical data, which tells them how sales of particular lines were affected during different weather conditions in the past.
Mark Aylwin, supply chain director for Safeway, says three days' warning is all the time needed by the supermarket to optimise store lay-outs, product stock and promotions around the weather. "We manage our supplies centrally and can make decisions that affect all 480 stores overnight. When the board meets on a Monday the first question is always what's the weather going to be like? The whole business is focused on it and we're trying to extend that culture to our suppliers as well."
Aylwin says the most important areas where stock and promotions must match weather conditions are in salads, beer, ice cream and fresh meat.
"That's where the big money is, so you've got to get that right. But being on the ball with the weather means you can also get a massive uplift in smaller lines, like hair-removal, facial tissues and hay-fever remedies."
Aylwin says sales of hair-removal cream can leap by up to 1400% in hot weather, baby wipes and women's razors can jump by 40% and salads a massive 500%. With these type of uplifts possible, Safeway is exploring more sophisticated ways of optimising its weather preparedness. A new system whereby store managers are sent weather-information text messages to their mobile phones is being tested, for example.
While the major supermarket chains have integrated weather information into supply chain and stock control management,the extent to which it is linked to marketing plans is less clear. Hearth admits: "Using weather data in business is still more of a stock-control than a marketing issue, but real gains can be made by linking it more closely to marketing strategy. Generally, brand owners haven't woken up to the fact that they can use weather information to drive promotions and campaigns around times of peak consumer demand."
Hearth cites a recent successful use of weather information by Sainsbury's, which ran a barbecue-themed radio campaign in the days running up to a hot June weekend. Radio is particularly suitable for running quick turnaround ads like this, and many advertisers of weather-sensitive products and services negotiate special 'temperature package' media deals, whereby their ads are held in reserve and broadcast once the temperature rises above a certain point.
Although Hearth asserts that brand owners are less sophisticated in their use of weather data (and Safeway's Aylwin agrees, saying he gets "frustrated at their relaxed attitude when we take it so seriously") some argue this is too simplified a view.
Andrew Marsden, category director for Britvic Soft Drinks, prides himself on being an experienced marketer of weather-sensitive products, having worked with soups at HP Foods before joining Britvic in 1997. For those interested in the temperature 'trigger points' for both categories, Marsden says sales of soup leap exponentially once the thermometer dips below 15 degC, while soft drink sales soar above 20 degC.
Marsden retorts that the suggestion that brand owners do not pay enough attention to weather information is "a gross overstatement, showing that people don't understand how manufacturing capacity is managed". Marsden says a company like Britvic which 'produces to stock' (the opposite of a manufacturer of a perishable product, like salad, which 'produces to order') has to carefully balance its marketing and production strategy.
A knee-jerk reaction to a weather forecast, with a sudden promotion and manufacturing push, can create a logistical headache. Marsden says: "We don't have an infinite capacity to produce, so we have to be careful." He adds: "There's no doubt that weather is important, but we base our decisions on seasonal differences, looking at annualised patterns over the past 15 years. Frankly, I still don't think the weather forecasts are robust enough to shift us from that."
Unilever's ice-cream division, Wall's suffered when it relied on weather data. Ten years ago, it ran out of water-ice products, like Calippo, when an advance weather forecast predicting low temperatures and little sun turned out to be incorrect. Wall's had scaled back production and the ensuing heatwave landed it in trouble. As the temperature reached the point where consumers favour the thirst-quenching water ices over conventional ice cream, Wall's sold all its stock.
A Wall's insider says: "The difference between a good and bad spell of weather on the ice cream industry is massive and the logistics of planning for what is essentially an impulse purchase is extremely difficult."
Obviously, with weather forecasting products to sell, it's no great surprise that the Met Office is keen to stress the financial importance of paying close heed to meteorological information. However, Hearth insists that as some areas of business - like the large supermarket chains - are able to show, the returns achievable from planning around the weather surely mean that others will follow.
He argues: "As shareholder pressure to maximise returns on investment intensifies, every business will be looking for that extra competitive edge and I argue that the 'weather edge' will become more important. In the past the weather has been a great excuse for not hitting sales and profit targets, but now that can be turned on its head, as we see companies proactively using weather data to drive demand, sales and profit."
WEATHER SENSITIVITY BY PRODUCT
Retail-sector opportunity Total value % potential
of sector total sales
(pounds m) increase
Meat and meat products 812 6.7
Fresh produce 419 5.6
Soft drinks 331 5.3
Ice cream 73 5.2
Chilled food 295 4.9
Dairy products 399 4.9
Processed fruit and veg 211 4.2
Frozen food 181 3.6
Fish 82 3.6
Bread and cakes 283 3.2
Total grocery 3086 4.9
Clothing 1558 5.7
Source: Datamonitor Weather Model
5 SECTORS MOST AFFECTED BY THE WEATHER
Once temperatures exceed 25 degC, sales of tubbed ice cream drop, while sales of hand-held ice creams increase exponentially. The reason is that people don't think they will get the tubs home before the ice cream melts. If the mercury rises even more, more consumers switch from ice cream stick products like Magnum and opt for more refreshing thirst-quenching 'water ices' like Calippo. The sun is the critical factor with ice cream - more will sell on a sunny cool day than a cloudy warm day. During a recent hot spell, Safeway saw sales of ice pops soar by 500% when it sold 1.5million in a single week.
Salad items are probably the most weather-sensitive products of all, and due to their short shelf-life - notoriously hard to plan for. Safeway says any salad item can rise by 500% during hot weather. Retailers have to be particularly accurate with their weather prediction when it comes to sourcing items such as tomatoes - as farmers have to ensure the produce is ripe.
Barbecue kits and related products grow incrementally above 24 degC. On the hot weekend of May 30/June 1, 2003, sales of disposable barbecues at a major supermarket leapt by 200% and barbecue meat by 300%. This summer, Sainsbury is running tactical poster and radio ads for its barbecue ranges, timed to coincide with good weather.
For every deg C increase in temperature between 18 degC and 24 degC, sales of carbonated soft drinks rise fourfold. Once the temperature exceeds 24 degC, soft drink sales drop off as people drink more water. Brand preferences also change, as thirsty consumers seek cheaper alternatives.
Depilatory brands sell far faster in warm weather. Safeway reports that hair-removing creams like Veet can see sales soar by as much as 1400% in high temperatures, while lady shaves commonly increase by 40%. Louise Dale, brand manager for Veet, confirms that "hours of sunshine have a direct correlation on our sales". She says: "The Veet marketing team actively monitors the Met Office for high-pressure forecasts at the beginning of the week, so we can then alert the trade ahead of a sunny weekend in order to minimise out-of-stock items."