According to the German Weather Service (DWD), continuous rain is a “long-lasting precipitation event with predominantly uniform rain rates” in the lower single-digit range per hour – i.e. with rates of up to 5 liters per square meter.
Typical continuous rain in local latitudes usually affects a larger area. The DWD meteorologists warn of continuous rain in several stages if it is foreseeable that certain threshold values will be exceeded.
The highest level, warning level 4, is reached when rainfall amounts of over 70 liters per square meter in 12 hours or over 80 liters per square meter in 24 hours or over 90 liters per square meter within 48 hours are expected.
According to the DWD, heavy rain refers to large amounts of precipitation within a short period of time in a smaller area. The main feature of this is “the high intensity of precipitation” – during heavy rain, more than 5 liters per square meter fall in a short period of time.