It is my belief/understanding that well seasoned wood that gets soaked by rain or melting snow, say, is still quite "burnable". That is, the water will have to be boiled off before the wood can burn, so some heat is lost to boil water. But, when the water is boiled off we have again seasoned wood in the fire. Green wood has moisture as part of its molecular make up, from growing. Here too, this moisture has to be boiled away before the wood can burn and thus heat is lot, but worse, the green growth water also has other affects - perhaps it lowers the temperature of the combustion of the wood itself, causing the combustion products to contain unburned wood products, i.e., creosote. Anyone got the answer? My use of the information is on handling wood that accidentally got wet while being stored outside. I try to keep seasoned wood dry, but if it gets a little wet, I will still use in the belief that if I keep the fire box hot, there is no significant increase in creosote emission due to the wood being wet.