A percentage does not measure the amount of rain
Precipitation probability describes the chance of measurable precipitation during the stated interval and at the point represented by the forecast. A high percentage does not automatically mean heavy rain.
The operational definition can vary between products and providers. Meteo Interactive therefore shows the source, update time and time interval and avoids comparing percentages that refer to different periods.
Millimetres describe an amount
One millimetre of rain is equivalent to one litre of water spread over one square metre. A forecast value is a model estimate, not a guarantee that every point in the area will receive exactly that amount.
Showers and thunderstorms can create large differences over short distances. Read millimetres alongside probability, the hourly sequence and, when available, recent radar imagery.
A practical way to read the forecast
First note when the probability rises, then check the forecast amount for the same hours. Finally, see whether the signal persists across updates or changes quickly.
For weather-sensitive activities, always use bulletins and warnings from the competent authorities. An automated forecast is informative and does not replace an official notice.
Forecasts describe likely scenarios and do not replace alerts or official authority communications.