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Example of the claim:

I've been told that if you see cows lying down in the field, that means it's going to rain.

[...]

Pretty much "common knowledge" among the PA Dutch but that doesn't mean it's true.

Oddthinking
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Lehzer
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    While looking for a notability cite for this, I had to wade through answers from other Q&A sites on this very question. If we are going to make the Internet a better place, we need to make this an excellent answer. – Oddthinking Jul 16 '13 at 01:20
  • Users on a forum is enough notability? –  Jul 16 '13 at 17:43
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    In much of the Northeast United States this is a pretty common statement of "folk knowledge". I don't know how "notable" that is, but if you ask anyone who's grown up in cow country they'll have heard of it. – MattDMo Jul 16 '13 at 19:31
  • Possible (but unanswered) duplicate http://skeptics.stackexchange.com/q/5397/8755 – RedGrittyBrick Jul 17 '13 at 21:31

1 Answers1

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It is doubtful that there is much correlation. Cows lie down too often for other reasons to be a useful predictor of rain.

Cows lie down a lot

Cows are ruminants and lie down to chew their cud. They also lie down for other reasons including sleep. Cows lie down perhaps up to sixteen times a day. At any given time there is a 50% chance a cow will be lying down but they tend to stand up more in hot weather and perhaps tend to lie down more in cold weather.

Confirmation Bias

We humans tend to find significance in coincidences and, if primed by knowledge of this adage, might have stronger recall of occasions when cows were seen lying down prior to rain than for occasions when cows were seen lying down prior to no rain or when cows were seen standing up prior to rain.

We like our old adages

Some frivolous media have speculated that air temperatures often drop before rain and that this therefore supports the old adage. It is notable that the study they cite says no such thing and is more focused on heat-stress.

References

RedGrittyBrick
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  • Please reference "It is doubtful that there is much correlation" –  Jul 17 '13 at 21:29
  • @sancho: I haven't found any statistical studies but the third reference above contains *"Cows lying down in a field more often means they’re chewing their cud, rather than preparing for raindrops."* which I think supports the doubt of significant correlation. I agree it's weak. – RedGrittyBrick Jul 17 '13 at 21:34