There are so many factors that contribute, and barometer is one of them, but certainly not the "one" thing that turns them off. cold fronts, temp, wind, lack of wind, bluebird skies, clouds, etc. I think you can get the fish to bite if you slow down a lot, & put it in their face, but you have to go slower. I fished yesterday, during a cold front, high winds & bluebird skies, and didn't catch many, but caught a mess of 10. Only had 5 crappie, but caught some green carp also. We caught a few dink crappie also, but it was just slow. Personally I think a cold front does more to them than anything. This causes temperature drops, and makes them scatter. I'm not a pro or a guide (except for my wife & kids), but that's my 2 cents.