Adjective : an unfavorable wind. ,an unfavorable omen. ,an unfavorable development.    From Dictionary.com. 

'In thick mist, and under strong appearance of a settled rain (which however did not happen) I set out about 7 o'clock, for the purpose above mentioned, but from the unfavorableness of the day, I derived no great satisfaction from the review.    From Wordnik.com.  [A Portrait of Old George Town] Reference

Notwithstanding the unfavorableness of the late impressions, it is believed the New York elections, which are over, will give us two or three republicans more than we now have.    From Wordnik.com.  [Memoir, Correspondence, And Miscellanies, From The Papers Of Thomas Jefferson, Volume 3] Reference