When glued, is sinew more vulnerable to humidity than wood?

[Russ Mitchell]

In East-Central Europe, winter was THE campaigning season. The Cumans wouldn't campaign in the summertime, and in Lithuania the boggy, creeky terrain was simply impassable.

[Bede]

The slippery end of the steppe.

In the other seasons the humidity might have been a problem too except high summer. In winter, the moisture froze out of the air.

[Orda Khan]

Bede,
When you say weaker in higher humidity how much so would you say? Rather than its affect on fps, how much does it affect the cast in metres?
Wet weather is always going to negatively affect most bows or strings, even the fletchings for that matter if they are feathers. Here in South Wales we have more than our fair share of rain

As an example, we held a field tournament only last Sunday and it poured all day long (no way was I going to shoot in that!!) One of the guys was telling me how he left his bow strung to dry out; this is a modern recurve with fastflight string. The brace height was out by over half an inch. I suggested that it was not the best idea and that a better idea would have been to dry the string under no tension. My point here is that by the end of the day, even this modern bow must have been shooting with less efficiency.

There is an account of one engagement between Temujin (Chingis Khan) and Jamuka that was undecided due to the blinding snow.