The day was intensely hot, and at that early hour the fierce fire of the sun had rendered the atmosphere sweltry and oppressive.    From Wordnik.com.  [Blackwood's Edinburgh Magazine — Volume 53, No. 330, April 1843] Reference

They didn't lose any time about it either, for as soon as I gave the order it was all haul down and furl up; and, getting a good grip of the water, they started pulling like madmen, putting their hearts into every stroke -- although the day was so hot and sweltry that a fellow seemed to melt away into perspiration, even lying still in the stern-sheets of the boat, as I was, without moving a muscle.    From Wordnik.com.  [The Penang Pirate and, The Lost Pinnace] Reference

O horrible those sweltry places are.    From Wordnik.com.  [Georgian Poetry 1911-12] Reference