Definitions of Heavy Rain, Extremely Heavy Rain, Torrential Rain, and Extremely Torrential Rain in Taiwan Area by CWB.
1.Heavy Rain:
24-hour accumulated rainfall exceeds 80 millimeters, or 1-hour rainfall exceeds 40 millimeters.
2.Extremely Heavy Rain, Torrential Rain and Extremely Torrential Rain:
24-hour accumulated rainfall exceeds 200 millimeters, or 3-hour accumulated rainfall exceeds 100 millimeters; referring to Torrential Rain if exceeding 350 millimeters in 24 hours and Extremely Torrential Rain if 500 millimeters or more.