the.com/sultriness

means The quality of being hot and humid in a way that feels heavy, charged, or faintly seductive — whether in weather or in a person's manner.

from From 'sultry,' which emerged in the 1500s as a variant of the older word 'sweltry,' itself from 'swelter' — rooted in Old English 'sweltan,' meaning to die or perish, originally from heat. The word cooled from 'dying of heat' to simply 'oppressively hot,' and by the 1600s had picked up its second life describing smoldering, passionate temperaments — heat migrating from the air to the glance.