If temperature is <# ># then #

Hello, I'm a weather guy for the Air Force stationed in Honduras. i'm trying to make an easy excel tracker for the heat index here. I'm looking for a formua where, if c1 < 78 then d1=NONE, if c1 ≥ 78 < 81.9 then d1=1, ≥ 82 < 84.9 then 2, ≥ 85 , < 87.9 then 3, ≥ 88 < 89.9 then 4, ≥ 90 then 5. with all cells pertaining to c1 and d1. I would much appreciate any help, I had a full head of hair before attempting this.