At the south rim the average high is in the upper 50sF and the average low is in the mid 20s. See the link below for a TON of data from last year about that location. I don't think they have reliable weather data like that for the bottom of the canyon, but it will be noticeably warmer at the bottom than at the rim.
Mrs. Lift, also known as Momma, was the main antagonist of Throw Momma from the Train. She was Owen's old mother who mistreated him and his friend Larry. At the end of the film, it was revealed by Owen that she died from natural causes. She was portrayed by Anne Ramsey.
Her sister became legal guardian of her daughter Owen (born in on 26 April 1967) upon her death in 1974. Hated being called 'Mama' Cass, which she took as a derogatory comment on her 300+ poundage. Additionally, it bothered her that the moniker led many to mistakenly assume Cass was her last name.