Translation:It was cloudy this morning.
"From Old Japanese. Originally a compound of 此 (ke, “this”) + 朝 (asa, “morning”).
The initial /ke/ is an alternative form of the initial /ko/ (此, “this”) seen in words such as ここ (koko, “this place → here”) or これ (kore, “this [nominal] → this”), and the final /sa/ is a contraction from */ke.asa/ to /kesa/ with the medial -a- falling out, as Old Japanese did not permit vowel clusters.
The use of the kanji 今 (“now”) instead of 此 (“this”) is an example of jukujikun."
It's just that the Japanese sentence is in plain past. Also, I'm not sure if Japanese even has perfective tenses.
And "this morning it has been cloudy" sounds weird. You would either say "it has been cloudy this morning" or "this morning has been cloudy", since the "it" in this sentence is a stand-in for "this morning" and is therefore unnecessary if "this morning" is already at the beginning of the sentence.