According to a recent survey by the UK Met Office, over 60 per cent of the British public believe that cows lying down is a sure sign of rain.
Perhaps the most common theory is that cows are able to sense the approaching rain, either through the increased moisture in the air or the accompanying drop in air pressure, and lie down to keep a patch of dry grass for grazing. Another theory emerged in 2013 when a study in the US showed that cows tend to stand in hot weather, as exposing more skin allows them to cool off more effectively. This led some to hypothesise that the chill in the air that often comes before rain could encourage cows to lie down to conserve heat.
In truth, however, there is no scientific evidence for this piece of weather folklore. The most likely explanation for any correlation between cows’ behaviour and the weather is probably simple coincidence – cows spend up to half of their time lying down, either to rest or to chew their cud, so there’s a 50:50 chance that they’ll be lying down at any given moment, come rain or shine. As herd animals, cows tend to mimic each other’s behaviour, upping the odds that you might see a whole herd lying down before a downpour.