I read in wordreference.com:
Note: Masculin ou féminin mais invariable.
Cette après-midi j'irai à la patinoire.
Why duolingo marks cette après-midi as a mistake?
Both "cet" and "cette" après-midi are accepted.
cette was marked wrong for me
Is <<pleuvoir>> reflexive in this case? Is it always reflexive? I ask becase the sentence I see uses the construct <<s'il va pleuvoir>>.
You may have figured it out but there is nothing reflexive about this sentence. The "s'il va pleuvoir" expression only means "if it is going to rain".
I wrote «I don't know whether it is going to rain in the afternoon» . In my view it means exactly the same as «this afternoon».
The sentence is accepted with either "if" or "whether".