London commuters will soon start noticing a change to the billboard adverts greeting them on their journey into the city.

The huge posters at stations and at key commuter points across the capital are about to get a major makeover to bring them into the digital age.

Usually plastered with an old-school poster ad made of paper, 40 new sites belonging to out of home (OOH) ad company Clear Channel will become digital billboards – but with a major technological twist which makes them more than just a static poster on a digital screen.

The technology behind the screens will serve ads that can respond to any number of factors in the surrounding environment – from temperature, time and pollen count to popular Google search terms in the local area.

Adding this contextual relevance offers huge potential for brands, but also means Londoners will see ads more appropriate and relevant to them than ever before – targeted, rather than one-size-fits-all in a similar way to the ads we see online.

Clear Channel’s commercial director Chris Pelekanou offers up a tasty example of how this could work. “When the temperature drops below a certain degree, retail sales data shows soup sales go up. The new screens will be able to detect this temperature trigger and could instantly serve up an ad for Heinz, for instance.”

Information which can be fed into the new network of billboards, known as the London Wrap because of the strategic locations circling the capital, includes almost any type of data such as retailer epos (electronic point of system) information, the OOH industry's specialist audience information and even mobile data.

“The screens are only 20 per cent, the rest is 80 per cent, what you can’t see,” says Pelekanou of the technology.

Its potential has yet to be fully realised until the new billboards are in place. However, one test on the company's premium site in Picadilly saw huge success, picking up a string of ad industry awards and public attention.

Feeding in flight information data, British Airways was able to show an ad which played only when a BA flight passed over the billboard. It might sound pretty standard- until you see the ad itself, which featured a child pointing to the plane in the sky as it flew over.

The same technology is also behind the recent ad on Clear Channel's network of bus stop screens for Walkers crisps and featuring Gary Lineker appearing to respond to people’s actions and interact with them.

Google has also experimented with the technology by showing people an ad which displays search terms made in almost real time within the area of the billboard.

The technology brings into the real world behavioural targeting more familiar from online ads. How many times have you seen an ad for something you’ve just been looking to buy on a shopping site, only for it to follow you around the web?

Is there a worry such specific targeting could become a little sinister though? “You have to be transparent about it, but consumers will get used to it,” says Pelekanou, adding that even with mobile data, all the information being fed into the London Wrap is anonymous.

New screens will be in place in Brent, Enfield, Hackney, Kingston, Lambeth and Waltham Forest this week, with all 40 due by the end of the year in almost every London borough. So be prepared to start noticing those ads on your way to work.