"Brrr-ace yourselves! Britain to shiver in -20C in WEEKS as councils stockpile extra grit". So the Mail on Sunday warned us in October. Blizzards, snowdrifts, locusts with the faces of men and the teeth of lions: we would become, it cheerfully assured us, prey to every nightmare nature could devise.

Last week the story flipped. "December has sprung! Spring blooms arrive early and autumn blossom lingers... so what happened to our winter?" I scoured the text but could find no mention that the Mail had forecast the polar opposite.

This is the newspaper group which led the crowing about the barbecue summer that never was. In April 2009 the Meteorological Office announced that "summer temperatures across the UK are likely to be warmer than average and rainfall near or below average for the three months of summer". In the event, the waters prevailed exceedingly upon the earth. From its offices on Mt Ararat, the Daily Mail called down the wrath of God on the weathermen, who had been proven "hopelessly wrong" and were now "left red-faced".

There are plenty of red faces in the newspaper industry, but they are not the result of embarrassment: an emotion as rare in this business as summer snowflakes. Most of the papers that basted and grilled the Met Office for its barbecue summer forecast predicted a sleighbell winter. The Sun, for example, announced that "Britain will shiver through a 'Siberian December'". The Express foresaw "a big freeze", beginning at the end of October, which would be "as severe and sustained as last winter's" and bring "record low temperatures".

Ours was, as it turned out, the second warmest autumn on record, while temperatures in December were a little higher than average. So where did the Siberian forecasts come from? According to one of the journalists who ran this story, they originated with the secretary of state for transport. During the Conservative party conference, Philip Hammond allegedly told senior journalists that there would be a terrible winter, but that he and he alone would save us from nature's fury by ensuring the roads remained clear. I have tried to check this story with the transport department, the defence department (where Hammond now resides) and his constituency office. Despite repeated promises, my questions remain unanswered.

The newspapers then asked the Met Office to confirm Hammond's prediction. It refused. (In 2010 it had decided to stop issuing long-range forecasts.) So they turned to people who would.

They chose to rely on two alternative forecasting companies: Exacta Weather, and Positive Weather Solutions (PWS). PWS boasts that it "has made the front page of the Daily Express thirteen times; the Daily Telegraph seven times; and the Daily Mail and the Sun once". Between 26 September and 1 October, it says, it "was quoted every single day in the Daily Express". It told the papers that late October and November "are looking colder than average with freezing temperatures, severe frosts and the chance of snow". Exacta, on which the Mail relied for its predictions of icy doom, warned of a "severely cold and snowy winter". "It is likely that temperature and snowfall records will be broken".

Who are they, and what are their credentials? I have been trying to obtain answers from Exacta since 20 December, without success. Among other questions, I asked whether it is true that the company consists of one undergraduate student and a computer.

PWS was more forthcoming. It admitted that its forecasting record had not been independently audited, and agreed that this was a failing. It also admitted that it does not keep a record of its prior forecasts on its website, which means that the public has no means of assessing its hit rate. But it failed to provide the qualifications or identities of the "independent meteorologists" it uses.

Both companies seem to publish only positive results. Exacta, for example, tells us that it correctly forecast strong winds this winter. It forgot to add that it also forecast severe cold and snow.

Unlike the Met Office, the alternative forecasters are neither roasted nor frozen out when they get it wrong. In 2010, for example, the Daily Mail announced that "the country really is on course for a barbecue summer". This time, it told its readers, the prediction "comes from a forecaster with a somewhat better record on the subject than the poor old Met Office". This was PWS – which has no published record at all. PWS told the Mail that "there will be stifling temperatures, making it possibly the warmest UK summer on record". In fact it was an unremarkable summer, but there were no "red faces" at PWS. Nor has Philip Hammond been denounced as "hopelessly wrong".

There is a subtext at work. The Met Office, like the BBC, is the subject of intense tabloid hostility, because it refuses to accept the consensus in the rightwing press that man-made climate change is a myth. Perversely, it prefers to rely on data. The incompetence of the Met Office and the superior skills of other forecasters are now part of the litany of climate change denial. Weather forecasting, in the hands of the press, has become a political science.

• A fully referenced version of this article can be found on George Monbiot's website