I don’t recall this neat little adage featuring in any of my meteorological training courses. But it’s certainly one for the back pockets of anyone joining in with the Great British pastime. Which pastime? Glancing to the skies and having a precarious stab at not getting wet!
… if it’s raining when we emerge from bed, it’s a fair estimate that it will stay damp for three or four hours
Most of our rain comes either in the form of short-lived showers or from longer-lived fronts. Let’s not worry about the showers, as they’ve often gone in the blink of an eye (or perhaps more realistically, a few minutes). Typically, though, the broader frontal rainbands – you know, the ones shown by red semi circles or blue triangles on the weather map? They’re, say, 80 miles wide and come cruising in from the Atlantic. They will be blown across the UK at about 25 miles per hour.
So if it’s raining when we emerge from bed, it’s a fair estimate that it will stay damp for three or four hours before brighter weather follows by late morning. And feel free to replace 7 and 11 with 10 and 2 etc… All around the clock, in fact.
But, annoyingly, fronts sometimes narrow, they sometimes expand. They can speed up, slow down and even go into reverse. This makes the method far from fool-proof. So if you do pull this adage from your bag when preparing to go out for the day, perhaps carry an umbrella in there, too.