I watch for signs of rain. I suppose I could watch on TV, but since I don't care to sit in front of "the box", I look around me. My 3 best signs for rain begin with aching joints, then noting that all the neighbors cows are lying down in a crowd in the pasture. The third sign of impending rain is when leaves on trees turn over and show their underside. There are a lot more..
I got to looking for rain folklore, and this is what I found..

• birds fly lower than usual
• crickets sing louder than usual
• frogs croaked more
• cats licked their bodies more
• worms come up out of the ground
• animals become restless
• bees stay close to the hive
• fish bite more readily and are nearer the surface
• smoke in chimneys blows down
• flies cling to the window screens
• flies are more bothersome before a rain
• a halo around the sun or moon indicates rain
• no dew on the grass at night

• some people can smell it and feel it

Of course if you live in Seattle....
There is an old saying "When the wind is blowing from the east, 'tis not fit for man nor beast. I've found that to be very true.
Matthew 16 says 'when it is evening , ye say it will be fair weather; for the sky is red.
And in the morning it will be foul weather today; for the sky is red and lowring'.
This is where we get the adage "red sky at night, sailor's delight; red sky in the morning sailor take warning".
Who needs a meteorologist?