Moderate to heavy rainfall can be defined based on the rate or amount of rain per hour or per day:
- Moderate rainfall is typically in the range of about 2.5 mm to 7.5 mm per hour, or about 11 to 30 mm in a day.
- Heavy rainfall generally means rates greater than 7.5 mm per hour, sometimes defined as 25 mm or more per hour, or about 31 to 70 mm in a day.
Different meteorological agencies may have slightly varying thresholds depending on the context, but these ranges are commonly used. Moderate rainfall leads to rapid puddle formation and flowing downpipes, while heavy rainfall can cause significant water accumulation and potential flooding. Heavy rainfall in some regions is defined as rainfall exceeding 100 mm in 24 hours and is associated with risks like floods and landslides.
Thus, moderate to heavy rainfall refers to precipitation intensities and amounts that range roughly from just over 2.5 mm per hour or 11 mm per day up to very intense rain cases exceeding 25 mm per hour or 70 mm per day and beyond.
