Recently one headline told the country that the UK "disappears" under a "551-mile wall of rain and snow", with weather maps turning green and red for dramatic effect. On 5 October the Met Office published a weather headline review that examined it against the actual forecast. The short version: changeable autumn weather, yes, an unbroken wall, no.

The wall, the vortex and the plunge

It is a fine headline. It has a number, a structure and a sense of menace, and nobody can accuse it of being vague. Several other headlines going round the same week used words like "smashed", "plunge" and "dire warning", which makes for a lot of drama before breakfast.

The Met Office went through them one by one. On the wall, it says the forecast shows bands of rain crossing the UK followed by showers, with the wettest conditions most likely in the north-west and relatively little rain in the south-east from Saturday 10 to Monday 12 October. Strong winds are possible, especially in the north. Its summary is "changeable weather with rain, showers and a likely interval of drier conditions, rather than the whole UK disappearing beneath an unbroken wall of rain and snow". On the "plunge" in temperatures, it says the word "may overstate the scale of the change". It calls the pattern "recognisably autumnal", not an exceptional cold spell.

That is the honest weather. Now the bit underneath the hype that is true.

A record-breaking El Niño

The headlines were riding on something real. On 22 September the Met Office said the developing El Niño in the Pacific had exceeded previous records. It called it "the strongest event in the observational record", and the event still had several weeks to go before its peak.

The same post says El Niño can influence weather in Europe through remote atmospheric connections, and that as the event approaches its winter peak there is an increased likelihood of wetter and stormier conditions across north-west Europe, including the UK, during autumn and early winter. It adds that, later in the season, El Niño is associated with an increased risk of cold snaps.

What the outlook actually says

The Met Office is careful with its wording, and it is worth being equally careful here. Its September long-range post says current evidence suggests "conditions later this autumn and into early winter may be more unsettled than is typical for the time of year". The three-month outlook puts the chances of a warm and wet autumn at around one-and-a-half to two times higher than would normally be expected, with an increased likelihood of windy conditions later in the season.

Two caveats matter. First, the headline review says El Niño can increase the likelihood of wetter, stormier and generally milder conditions in late autumn and early winter, while a weaker stratospheric polar vortex later in winter may raise the chance of cold weather. These are "shifts in probability rather than guarantees". Second, in the Met Office's words, "El Niño is only one of several factors affecting the UK's weather." Its own advice is that confidence in specific patterns for late October and early November remains low.

So the useful reading is that the dice are loaded a little towards unsettled weather, with a possible cold snap later, and nobody can say when or where. You plan for a range, not a date.

What to do now

A wetter, windier autumn and a possible cold snap later are not a reason to panic. They are a reason to spend an hour in October on outdoor plant that is easy to forget.

  • Clear the outdoor units. Leaves and debris collect around AC and heat pump outdoor units in autumn, and a blocked coil or a restricted fan makes the unit work harder. Keep the space round it clear and make sure nothing is stacked against it.
  • Check the drainage. Condensate and defrost water has to go somewhere. Look at drain lines and the ground under the unit, and make sure they are not blocked or likely to hold water.
  • Look at the fixings. Brackets, feet and covers can work loose over a summer. Strong winds find them.
  • Commercial refrigeration plant. Clean condensers, check that outdoor equipment is not boxed in by stored goods or waste bins, and review what you would do for stock if the power went off. We covered that in our note on storm names and power cuts.
  • Get faults looked at early. A unit that was making odd noises or tripping in the summer will not improve in the first frost. If something is wrong, arrange an air conditioning repair before the weather turns, and for fridges and cold rooms, commercial refrigeration maintenance is the place to start.

The Met Office will keep updating its outlook as the El Niño develops, so check its forecasts and warnings rather than a map with a number on it.