thats kind of a tricky question,, not sure there is one answer,, poundage might vary with different moisture content,, bow is less likely to take set when dry, if it does take set because too much mositure, I think most the time it wont go back,, that bein said,, sinew bows can loose poundage and then when dry out, regain reflex and poundage, so its tricky,
if you keep your bow at reasonable humidity, it should not be an issure,, if your on a camping trip and your bow is in the rain every day for a week, and you are keeping it strung to hunt, it might take more set than a bow that is just shot on sunny days for fun,, osage seems to be resistant to moisture,, but my hunting bow I have had for 25 years follows the string more than most would like,, but still shoots nice,, its not a rocket launcher,,but at 58#@28,,, thats as much as I need,,,