When it's dynamic, expect means something like 'waiting for'. Dynamic expect: I am expecting guests this weekend. (Guests are coming so I am preparing/ waiting for their arrival.) Stative expect: I expect that it will rain. (More of a guess or a thought. I think it will rain.) 'Expect' can also be used dynamically in the case of pregnancy. We can say, "She is expecting a baby" (meaning: she is pregnant).