"I take it, it's raining" should be accepted. It's not meant to be literal, but it does work in English, and if the German and English have a nearly direct equivalent, that should work. Unfortunately, "Assume" didn't readily spring to mind at the time. Another one should be "I gather it's raining"

My answer of "I suppose it's raining" should be accepted.

I presume it is raining is not accepted?!