in the paragraph beginning, "Summer was on the way...", Scout describes summer by comparing it to a series of other things that remind her of the season. What literary term best fits her description?

I think you have a series of metaphors here:

Summer was on the way; Jem and I awaited it with impatience. Summer was our best season: it was sleeping on the back screened porch in cots, or trying to sleep in the treehouse; summer was everything good to eat; it was a thousand colors in a parched landscape; but most of all, summer was Dill.