A predicate noun or pronoun is part of the predicate of a sentence rather than being the subject and serves to modify or describe that subject.
Summer days seem an illusion.
The words "Strawberry Days" in the phrase "The city calls its summer festival Strawberry Days" act as a predicate nominative. A predicate nominative is a noun or noun phrase that follows a linking verb (in this case, "calls") and renames or identifies the subject ("its summer festival").
the sultry part of the summer
It could be with an apostrophe: A prosperous day's ahead. (day's = day is) Otherwise it is not a sentence at all, as there is no predicate.
nnkn
The simple subject is February; the simple predicate is has.
Summer Days happened in 2006.
At the beginning of summer, days are longest.
It inevitably rains on days when we are off work. Whenever you wash your car, a bird inevitably poops on the finish.
I love walking through the trees' shade on hot summer days.
225 days
1. Summer days are longer than winter2. Summer days are hotter than winter
There are reckoned to be 92 days in the northern hemisphere summer.