Keep the place and period beside the percentage
The Met Office’s forecast guide explains a precipitation chance as the chance that precipitation falls at some point during the stated period. Its example of 70% means a seven-in-ten chance of that event. It does not define a share of the period that will be wet.
When a forecast appears in a programme or shared graphic, retain the location and time interval with the number. A percentage cropped away from its place or period loses essential meaning. Do not turn an hourly probability into an all-day statement without checking the all-day forecast.
Do not calculate wet minutes from the chance
In an illustrative one-hour forecast, multiplying 70% by sixty minutes would produce forty-two minutes. That arithmetic does not establish a predicted shower length. The Met Office explains that precipitation can extend through a period or fall in a short burst.
Probability, duration and intensity are separate questions. Use the weather symbol and the accompanying explanation for information about the kind of conditions expected; do not ask one percentage to supply every answer. This article gives no forecast for an actual place or date.
Notice which quantities refer to an instant
The same guide distinguishes quantities such as temperature at the stated time from weather symbols, precipitation chance and gusts that describe the interval beginning at that time. A viewer comparing two columns should therefore read what each quantity represents before treating the entire column as one instantaneous picture.
If a broadcaster’s graphic uses a different period or provider, read its own explanation rather than assuming every layout has the same convention. A familiar icon or percentage sign is not enough to establish identical definitions.
For a viewing note, use a complete description: the stated chance, location and period, with any separate information about intensity or timing kept separate. Recheck the current official forecast for a real decision, since a saved programme or screenshot can preserve an earlier forecast. The goal here is to read the graphic accurately, not to infer certainty, precise wet minutes or a new forecast from an old recording.
Questions answered
Does 70% mean rain for seventy percent of the hour?
No. In the cited guide it means a seven-in-ten chance of precipitation at some point in the stated period.
Does the percentage by itself give rainfall intensity?
No. Probability and intensity are different quantities; read the accompanying forecast information.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.