A half mast flag should be flown from sunrise to sunset for the durations of the order.
A half mast flag should be flown from sunrise to sunset for the durations of the order.

National Days of Remembrance

Flags will be flown at half mast on National Days of Remembrance
Flags will be flown at half mast on National Days of Remembrance

National days of remembrance regarding military events like Patriot Day, Pearl Harbor Remembrance Day and Memorial Day typically carry a half-mast, or half-staff, order. With the exception of Memorial Day, when the half-mast order ends at noon, the American flag is at half-staff from sunrise until sunset on the days of the order.

Presidential Proclamation

The President can dictate flags be flown at half mast.
The President can dictate flags be flown at half mast.

The U.S. President can dictate by proclamation when, and for how long, the American flag is flown at half-mast. According to the Department of Veterans Affairs, the flag should fly at half-staff for 30 days following the death of a current or former president, and for 10 days after the death of the vice president and other government officials.

Bottom Line

US Flag at half mast.
US Flag at half mast.

For a half-mast order issued for a day of remembrance, the flag flies accordingly between sunrise and sunset for only that day. For a Presidential proclamation, the event leading to the order will dictate the number of days the flag will fly; but the sunrise-to-sunset rule remains in effect.