I definitely think pressure effects fish. In fact, it's probably a big part of the explanation for how you can fish the same lake (or river) on consecutive days, using the same gear and techniques, and have vastly different degrees of success.
When it comes to nailing down the patterns, good luck is all I can offer. So far, there's not a conventional "rule" about weather and fishing I haven't seen broken at least a couple times. There do seem to be some "rules" that generally hold true more than others. For example (in my experience):
*Wind from the East, fish bite the least. Whether it's got anything at all to do with the wind or not, I usually find few, tentative bites that don't stick in an East wind. This is almost an actual rule for fall salmon, but not quite. Probably has something to do with barometric pressure changes, but who really knows?
*River on the rise? Stay home and tie flies. Sure, you can intercept moving fish in these conditions, but most of the time, they seem too bent on traveling to stop and bite anything (or something...).
*Full moon? Try again soon. Especially for resident fish, I find a full moon to be a consistent bite killer. I did have my best ever numbers day on steelhead the day following a peak full moon, but I have yet to have an even moderately productive day following a full moon since. I usually try to plan my fishing around full moons and go clamming instead. ***I am told the reason trout fishing sucks during the daylight on full moon days is that resident fish eat at night on full moons, so they're less apt to eat the next day. Perhaps that's why I get so many weak, tentative bites on those days. I am also told that fishing lakes at night on a full moon can be really good, but I've yet to try it.
So, you see, as Sg said, it's clear that fishing is better on a slightly rising or dropping barometer, unless it's not.