This is what the Dept of forestry published on this.
Less humidity obviously is better when drying, but my personal experience is constant air flow will speed up drying. The west coast Alder is similar to Poplar in hardness and when we milled it in March, we were able to use in November. But, I was in the mountains of Calif where humidity is low and wind is always present at night. Anyway, this pdf is a good reference.