2000 GMC Safari Misfire when when engine is cold in Morning

I noticed since the rainy season started here in Florida that my engine will misfire or hesitate a little before the engine is completely warmed up and it only seems to happen early in the morning. I'm thinking that something is damp with the morning condensation, maybe the plug wires are shorting out across the block or against each other and need replacement. The problem doesn't exist any other time of day or night, just early morning. The plugs are fairly new and the cap and rotor are new. Wires might be original.