24 Christ then was crucified for us, who was judged in the night, when it was cold, and therefore a fire of coals was laid. He was crucified at the third hour; and from the sixth hour there was darkness until the ninth hour; but from the ninth hour there was light again. Are these things also written? Let us inquire. Now the Prophet Zacharias says, And it shall come to pass in that day, that there shall not be light, and there shall be cold and frost one day; (the cold on account of which Peter warmed himself;) And that day shall be known unto the Lord; (what, knew He not the other days?
Days are many, but this is the day of the Lord's patience, which the Lord made;)— And that day shall be known unto the Lord, not day, and not night: what is this dark saying which the Prophet speaks? That day is neither day nor night? What then shall we name it? The Gospel interprets it, by relating the event. It was not day; for the sun shone not uniformly from his rising to his setting, but from the sixth hour till the ninth hour, there was darkness at mid-day.
The darkness therefore was interposed; but God called the darkness night. Wherefore it was neither day nor night: for neither was it all light, that it should be called day; nor was it all darkness, that it should be called night; but after the ninth hour the sun shone forth. This also the Prophet foretels; for after saying, Not day, nor night, he added, And at evening time it shall be light. Do you see the exactness of the prophets? Do you see the truth of the things which were written aforetime?
Source: Catechetical Lectures (New Advent)