I can’t stop talking about the weather!  And I could discuss grammar for hours too.

In english the verb “to discuss” does not need the preposition “about” before the direct object – in this case, the weather. I think I know the cause of the problem and it is the verb to talk. “ To talk about something” and „to discuss something” mean the same in english.

Take a look in the dictionary.  Discuss is a transitive verb,  which means it always needs a direct object in the sentence. Compare that with the verb “to talk”. Talk is one of those verbs which sometimes needs a direct object and sometimes does not. To talk means to say words aloud – in this case no direct object. However, to talk + about something means to speak with others about an issue. The verb talk needs the preposition about when used with a direct object.  Talk about and discuss about.