How to redirect grep output to a variable?

Question

I have some pipe. For example, I have this pipe:

user@user:~$ cal | head -1 | grep -oP "[A-Za-z]+"

For this pipe I get this result:

September

I want to store this result to a variable. I write the following commands:

user@user:~$ cal | head -1 | month=$(grep -oP "[A-Za-z]+") | echo $month

And I get the blank string. What is the problem?

Answer 1

 month=$(cal | head -1 | grep -oP "[A-Za-z]+")

or

 month=$(date +%B)