What exactly is the interval and duration of occurrence represented by the acronym TEMPO? When we look at this How to interpret BECMG and TEMPO in TAF? question, we see the following in the answer statement: "The TEMPO group is used for any conditions in wind, visibility, weather, or sky condition which are expected to last for generally less than an hour at a time (occasional), and are expected to occur during less than half the time period." What exactly does this statement mean? For example, when we look at the expression "TEMPO 0414/0418 -SHRA", will the shower rain last 4/2=2 hours or 1 hour? I would be glad if you explain.
Weather is dynamic and it doesn't always go along with the weather report.
TEMPO 0414/0418 -SHRA
This indicates that between 14z and 18z there will be rain showers coming staying less than one hour and then leaving.
Will the actual weather always do that. Nope. Hence it is good to get an updated weather report when you can.