Your choice of substrate will be the biggest influence on the humidity. What are you using? And what kind of enclosure is this? (ie. screen top?)

I use humid hides for some of my snakes- they really use & seem to enjoy them- like a "day at the spa"- .

As far as temps.- if yours were on the low end (88*) then a bump-up of 3* would have been worth a try, but not since your temps. are already too high.