The rain can definitely help improve the fishing for northern pike.  You can find plenty of pike in the shallows feeding on bait fish during the rain, but don’t rule out the deep water bite as well, especially during the summer and fall.  Bright colors and flashy lures tend to work better in the rain because of the low light conditions.  Pike are sight feeders, so make it easier for them to find your lures and you’ll catch more fish.  If you are using live minnows, try using them on a spinner rig or jighead and use bright colors to help your live minnows stand out.