Cows laying down is a good indication, but it would’ve been funny if I hadn’t specified that more than usual should be down. I think of cows as equal parts lazy as hungry. If a cow laying down were always a sign of rain, it’d be a constant downpour.

Another one is watching the dog.  They have better senses and can tell a storm is coming better than people by far.  However, some dogs won’t care.  One of the last 2 dogs I’ve had could be found hiding under the bed if a storm was coming.  The other would just be hanging around, being awesome.