2025 Hainan Flood Season: Cyclone, Rainfall, and Heat Outlook
Hainan Province is predicting to face 6 to 8 typhoons during the 2025 flood season, according to a recent press conference held by the Hainan Provincial Meteorological Bureau. This season’s climate conditions are forecast to be more severe than in 2023 but an improvement over the extreme weather events of 2024.
Delayed Rainy Season with Near-Normal Rainfall
The 2025 rainy season is projected to begin in mid-May, about 10 days later than average, and end in late October, also slightly delayed. Despite the shift, total rainfall during the flood season is expected to be close to normal levels.
However, localised rainstorm and flooding events may be marginally more severe than usual.
From January 1 to April 27, average rainfall across the province was 107.2 mm, which is 34.5% below the long-term average. While Danzhou recorded a relatively high 260.8 mm of rainfall, areas like Lingshui and Changjiang saw deficits of over 70%. Only Baisha, Chengmai, and Danzhou had above-average rainfall.
6–8 Tropical Cyclones Expected, 1–2 Likely to Make Landfall
Between May 15 and November 15, 6 to 8 tropical cyclones, including tropical depressions, storms, and typhoons are expected to influence Hainan. This is near the average of 7.8 cyclones annually. Of these, 1 to 2 may make landfall, which is in line with the historical average of 1.6. The intensity of these storms is also expected to remain close to normal.
The first cyclone of the season may not arrive until mid-June, about 40 days later than usual, while the last may extend into mid-December, roughly 20 days later than average. While severe typhoons are unlikely, the possibility of one or two stronger systems affecting the province remains.
Cool Start to the Year, but Warmer Flood Season Ahead
The first four months of 2025 were cooler than usual. The average temperature across Hainan was 21.5°C, 0.5°C below the seasonal norm. Regional averages ranged from 20.0°C in Qiongzhong to 24.9°C in Sansha. Except for Baoting, which remained consistent with historical norms, all areas were slightly cooler.
Temperature deviations by month were:
January: 0.3°C below average
February: 0.1°C below average
March: 1.3°C below average
April (up to the 27th): 0.4°C below average
Despite the cooler start, flood-season temperatures are expected to rise above average, with more hot days than usual. However, the risk of heat-related disasters is expected to be slightly lower than in 2023 and 2024.
Comparison with Recent Years
2023:
5 tropical cyclones, 1 landfall
14 regional rainstorm events
Mild cyclone damage, moderate flooding, more severe heat
Overall favourable climate
2024:
8 tropical cyclones, 2 landfalls
12 rainstorm events with higher intensity
Widespread and severe cyclone, flood, heat, and drought damage
Overall unfavourable climate
The 2025 season is forecast to be slightly worse than 2023 but a notable improvement over 2024.
Key Meteorological Risks and Recommendations
Heatwaves and Drought
Fifteen counties and cities have already experienced mild to moderate drought conditions. With temperatures expected to rise, summer may bring more episodes of high heat and dry spells. Authorities advise proactive measures including:
- Heat protection and cooling infrastructure
- Ensuring power and water supplies
- Forest fire prevention
- Scientific reservoir management
Severe Convective Weather
Hainan regularly experiences intense weather events like heavy rain, lightning, gales, and hail. These pose risks to life, property, and infrastructure. Residents and local authorities should:
- Reinforce public safety awareness
- Improve disaster readiness
- Protect agricultural and industrial assets
Typhoons and Flooding
Given the expected tropical cyclone activity and slightly heavier rainstorms, early preparations are essential. Local authorities are recommended to monitor typhoon developments closely, prepare for regional rainstorm events and optimize water resource allocation and flood control.
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