To me rain only has one bad effect on fishing and that's when it muddies the water in tidal inshore areas if you're fishing with lures. Rain, as mentioned, does sometimes come with east wind that improves beach fishing on our coast because all the bait is blown towards the shore not to mention it stirs up the beach wash and that gets the bottom feeders chewing. Pressure (low) does affect the fish also and when they feel it coming they turn on to feeding before the storm but once the low pressure and bad weather is here it usually shuts/slows down the catching.