Gutshot, I never thought about weather affect the ask solution.  I could see where it might cause the pores to tighten.  Maybe that why it took longer to looses the hair than I had read, cause I usually do most of fletching in the winter months. 
Now, the egg tanning solution is mighty touchy in the heat of the summer.  I did my first batch in July and had it in the carport in a pickle bucket.  I stirred it right on schedule.  I immediately started the second batch even though I was going camping in NC.  I put the lid on the pickle bucket to transport it to campground. I didn't stir on the trip down, then forgot about most of the next day.  It was "working" in that closed bucket.  It smelled terrible when I opened the bucket.  haha.  I washed the hides out and brought them home.  I re-stretched and dried them, but never finished the process.  Those are the ones that need to be done over to finish the process.  haha