Since my last visit, I acquired permission to another pond. It's .85 acres and is stocked with Bluegills and cats. I went early last week and tore up some nice, fat hump backed bluegills and several cats ranging about 3 pounds each.
I went back yesterday morning and got there at dawn. It didn't matter what I did, how I fished or what I offered. I couldn't get so much as a pick up. Nothin'! If I hadn't gone a few days before, I would have never believed there was the first fish in that pond.

Why do they shut down like that?

do they fertilize the pond? That alone may be it?

any aeration in the pond, or weeds? Could be the cat poo and the increse in water temperature decreasing the dissolved oxygen and increse of ph levels to the point of being inactive.

could be that they just weren't hungry 

Go get'em Jim!

I think you guys have identified the culprit with the change in weather. It's amazing how we respond to environmental conditions as we experience them when we step out to the  outdoors. I believe the fish have some sort of similar experience and their feeding/behavior activity reflects it. I think in this case they were sort of just on hold for a while waiting for conditions to become more favorable.
     I've heard it said before that on the way to lake one should observe the animal life on the way.  For an example if the cattle are lowing instead of feeding this may be an indication the fish are not feeding. I've never tried to verify any of this but another thing I've heard is concerning the barometer. I've heard that you can get an idea of the barometer by going to the bait shop and observing the minnow tank.