Counting the Day
As we think about the events central to Holy Week, it is important to understand what a day was since it is different than what we consider to be a day and many of the details recorded in scripture assume this understanding.
If someone asked you how many hours are in a day, you would answer 24. Jesus' answer to that question would be 12. As he taught, "Are there not twelve hours in the day?" (John 11:9). The difference lies in how Jewish time keeping differed from Roman time keeping. In Jewish time, the day is divided from the night. There are 12 hours in a day and 12 hours in the night. The night and the day together constitute a day, but the night comes first. It is written in Genesis, "And the evening and the morning were the first day", "And the evening and the morning were the second day", etc. Thus, a new day begins at sunset.
At the time of Passover, sunset is roughly around 6pm, so the day would begin roughly around 6am. The first hour being dawn, the third hour being at 9am, the sixth at noon, and so on. There are 12 hours in the day. The sixth hour is at noon.
The Roman Night Watches
The Roman night watch division was adopted after Roman occupation began in 63BC. The end of each watch was signaled by a trumpet signal as Jesus noted in Mark 13:35-36, "Watch ye therefore: for ye know not when the master of the house cometh, at even, or at midnight, or at the cockcrowing, or in the morning: Lest coming suddenly he find you sleeping".
In the way Jesus refers to the watches, they align with Roman times as follows:
At even - First watch - Sundown to 9pm
At midnight - Second watch - 9pm to midnight
At the cockcrowing - Third watch - Midnight to 3am (a trumpet call known as "the cockcrow" signaled the end of the 3rd watch and the beginning of the fourth)
In the morning - Fourth watch - 3am to sunrise
It is likely this 3am cockcrow signal of which Jesus refers to in his statement to Peter, "I say unto thee, That this night, before the cock crow, thou shalt deny me thrice." (Matthew 26:34)