Depends what species you are targetting, a cold front in early fall late summer usually helps the cold water species fishing like trout, but a cold front on warm water species usally means you have to fish slower for them. You have to trigger the predatory response in them, as they slow down.
A cold front went through here last night. This morning I stopped out at Lon Hagler reservoir about 7 a.m. right on the back edge of the front, still cold and windy. Caught & released 30 rainbows that hit on a little Mepps brass colored spinner, fishing at the water inlet. (The bad news: none of them over 11 inches. )
I have to say, these trout loved a cold front. I can always catch some trout there, but not like this. They were biting like sunfish.
Cold fronts definately slow the bite for most fish. It isn't the front itself in my experience, but the high and breezy sunny skies afterwards that are tough. Just before a front is usually great fishing unless your talking gale conditions.
For trout, cold fronts don't seem to have much effect, but trout are so vicious I don't think it matters. However, the high sunny skies following a storm are terrible times to fish for lake trout. Go figure.
I have never had troubles after cold front for warm water species. My wife and I went bass fishing Wednesday and caught several bass. WE just adjusted our presentations from fast moving jer baits to slow spinner baits. I believe that any fish can be caught after cold fronts just by adjusting your presentation.