|THE "WHAT DAY IS IT OVERNIGHT?" PROBLEM
METEOROLOGIST JEFF HABY
A minor problem that crops up time to time is the labeling of what day is the overnight hours. When a forecast
calls for a Thursday night overnight temperature, most of the overnight is often actually Friday from midnight until
the sun rises.
The way a calendar day is divided causes this confusion. Of course, nothing can really be done about changing when
a new day starts due to tradition. Instead of night time being split
between two days it would seem to make more sense to start a new calendar day close to when the sun rises
(i.e. make the current 6 A.M. the start of the new day and change the current 6 A.M. to 12 A.M.). This way, all to most
of the daylight hours would occur in the A.M. and
all to most of the night hours would occur in the P.M. of the same day. One described day would correspond to a
complete day and a complete night instead of a complete day and half of the night from two different days.
There are various ways to get around the night splitting problem. The first is common understanding. It is fairly
much common understanding that when Thursday night is mentioned for example, a person really knows this
is Thursday after sunset and Friday before sun rise. Second, the night could be called predawn of a particular
day (i.e. Friday predawn low will be 35 F). Third, references can be made using A.M. and P.M. (i.e. The Friday
A.M. low will be 35 F).