I been fishing one place for over ten years now.  I've seen smallies only during the rain.  It makes me wonder were are they the other times?  I'm in a large man made body of water thats a flowing stream that was dammed up.  I use the same baits all the time.

You weren't very specific about the type of structure in the water and the depths you are fishing but I will give it a shot anyways.  I don't have the experience fishing lakes or reservoirs for smallies as I do a lot of wading in rocky, shallow rivers but you can't go wrong with any of these:  Buzzbaits, Spinnerbaits, Crankbaits, Flukes, 3, 4, & 5 inch grubs and Senkos all work for me.  I am sure I am leaving out other popular baits, but this is my bread and butter for where I fish.  I would try some Yamamoto Hula Grubs in 4 or 5 inch and the wacky senko.  Add some lead nail in the Senko if you are fishing over 8 feet or so if you feel the need to. 

And next time you are fishing in the rain, throw a buzzbait!  I have had two of the best days fishing buzzbaits in the rain as the smallies were blowing up on it.

Are you shore-bound or fishing from a boat? Do you have electronics on-board, if you are fishing from a boat? What's the water clarity like? Temperature? Forage base?

If we have a few more details, we can probably help you out a lot more here. I'm in MA and fish the Quabbin a lot, so I'm familiar with reservoir fishing for smallies. Just not sure what kind of conditions you are being faced with. So, please fill us in!

Smallies can be unpredictable at times, they don't seem to hold to patterns like largemouth can. Maybe they are holding deep and only coming into the shallows when it rains to ****** bugs. I'm not too skilled in fishing for smallies in lakes though, so I could be way off!