fiddle sounds better when it's humid

For some time, I've been noticing that there are days when my fiddle sounds and feels much better than normal. It feels very smooth. This was the case last night at the Cantab, and I figured it must be that the humidity makes the horse hair pull more evenly. Today it still feels that way. Consequently, I've been playing it spontaneously for most of the last 4 hours.
Does anybody know if this really is due to the hair? I've also heard that the violins themselves sound better on humid days.