The AP Stylebook states that in most stories the exact time of a specific event or occurrence is not necessary. AP Style does, however, have specific guidelines to follow for those instances that do call for the time of day to be included and in what form they should appear. Here is a summary,
When to Specify the Time of Day
You should specify the time of day in AP Style whenever it gives the reader a better image of the scene that took place. For instance, did the tornado occur when people were home sleeping or away at work? It is acceptable to use a clock reading for the time in the datelined community, but AP Style states that using the terms “pre dawn hours” or “rush hour” are often more illustrative and beneficial to the reader.
You should also always specify the time of day when it is critical to the story. For instance, when will the baseball game be broadcast? What time is kickoff for the Super Bowl. When do the voting polls close?
What Clock Time Do I Use?
When you are giving a clock reading, you should use the time in the datelined community. If the story is undated, you should use the clock time in effect where the event happened or will happen.
The one exception to this rule is a national event that happens either on radio or television. In this case, you should always use Eastern time, followed by EDT or EST. You then should specify whether the event will be broadcast simultaneously or whether the times will vary dependent on the different time zones. As it is practical to do so, specify those times in a later paragraph.
Time Zone Abbreviations
AP Style states that the time zone abbreviations EST, CDT, PST, etc., should only be used after a clock time if,
- The story deals with travel or other activities, the closing hour of a polling station, or the time of a televised speech likely to affect groups across different time zones.
- The item involves a radio or television program.
- The item is undated.
- The item is advisory to editors.
Should I Convert to Eastern Time?
You should not convert the time of day from other time zones in the continental United States to Eastern time. If there is a high demand for the precise time, you can add PST, MDT, etc., to the local reading and other readers can from there determine their equivalent local time of day.
For stories outside of the continental United States where time is critical in the story, you should provide a conversion to Eastern time using the following form,
- The attack happened at 10 a.m. (5 a.m. EDT).
More time-related guidelines of AP Style,