The city of Haikou is on the northern edge of the torrid zone, and is part of the monsoon tropical zone. April to October is the active period for tropical storms and typhoons; most occur between August and September.May to October is the rainy season with most rainfall coming in September.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| 17.5 | 18.5 | 21.4 | 24.8 | 27.4 | 28.3 | 28.5 | 27.9 | 27.1 | 25.0 | 22.1 | 19.0 | 23.0 |
Average rainfall (mm):
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year Total |
| 22.8 | 32.2 | 46.2 | 96.9 | 177.3 | 209.8 | 200.5 | 211.6 | 278.4 | 178.1 | 90.2 | 41.8 | 1591.5 |
