The "Sauna" moniker is partly a product of geography. The landings took place in October, deep within the typhoon season. The beaches of Leyte were a sweltering landscape of thick, sticky mud and oppressive humidity.
Based on the likely subject matter, "OPMIKE" typically refers to (specifically the crucial amphibious operation during the Battle of Leyte in WWII), and the "Sauna" reference usually alludes to the intense heat, humidity, and steam caused by the tropical environment and naval bombardment during the landing. opmike sauna