It's just past 6:30 in the evening, but it's pitch black outside already.
It's been light outside by 6:30 in the morning lately.
この場合、次のような言い方ができますよ。
ーIt's just past 6:30 in the evening, but it's pitch black outside already.
「まだ夕方の6時半なのに、外はもう真っ暗だ」
pitch black で「真っ暗な」
ーIt's been light outside by 6:30 in the morning lately.
「最近、朝の6時半には外は明るい」
light で「明るい」
ご参考まで!