Shanghai Enters Plum Rain Season With Heavy Rain Forecast

Shanghai officially entered its annual plum rain season on June 18, 2026, as announced by the Shanghai Meteorological Bureau, bringing heavy rainfall, high humidity, and significant impacts on daily life during the Dragon Boat Festival holiday and the city’s high school entrance examination period. The arrival of the season — known locally as rù méi (入梅) — comes close to the historical average start date of June 19 but later than last year’s early onset on June 7, according to The Paper.

What Is the Plum Rain Season?

The plum rain season (méiyǔjì) is a distinct climatic phenomenon affecting the middle and lower Yangtze River basin, including Shanghai. It occurs in late spring to early summer when the East Asian monsoon brings a stationary front that lingers over the region, producing prolonged periods of overcast, rainy, and humid weather. The name derives from the fact that this period coincides with the ripening of plums.

Shanghai uses a strict three-part standard to declare the start of plum rain, as People’s Daily Shanghai reported in May: at least 3 of the 5 days before onset must have average temperatures of 22°C or higher; at least 4 of the first 5 days after onset must have rainfall; and the subtropical high ridge line at 120°E must be positioned north of 18°N.

Immediate Weather Impact

On the morning of June 18, light rain fell in Shanghai’s Jinshan and Qingpu districts, with the city experiencing mostly cloudy to overcast conditions and scattered showers throughout the day. Temperatures ranged from a morning low of 21°C to a daytime high of approximately 30°C, with relative humidity between 60% and 95% creating a muggy, oppressive feel.

Rain is expected to intensify significantly after midnight into June 19 — the Dragon Boat Festival holiday. The Shanghai Meteorological Bureau has warned of localized heavy to torrential rain accompanied by thunderstorms, short-duration heavy precipitation, and gale-force winds. Coastal areas, the Yangtze River estuary, Yangshan Port, and Shanghai’s coastal waters may experience wind gusts of 7 to 8 on the Beaufort scale from the night of June 19 through the morning of June 20.

Impact on Dragon Boat Festival and High School Exams

June 19 is the Dragon Boat Festival (Duānwǔ Jié), a major Chinese holiday. The heaviest rainfall is expected from late June 18 through daytime June 19, potentially disrupting travel plans and outdoor festivities. Authorities have advised residents to monitor forecast updates and take precautions against the weather.

Compounding the situation, Shanghai’s high school entrance examination (zhōngkǎo) is scheduled for June 20–21 — a critical event for tens of thousands of students across the city. The China Youth Network reported that while only brief light rain and mostly cloudy skies are forecast for the exam days, officials recommend that students and parents bring umbrellas and plan their travel time accordingly. Temperatures during the exam period are expected to range from 23°C to 28°C on June 20, rising to around 30°C on June 21.

Extended Forecast and Public Advisories

Looking ahead, Shanghai is expected to see continued rainfall next week, with another significant precipitation event forecast around June 22. Temperatures are expected to remain stable between 23°C and 28°C.

The meteorological bureau has issued public health advisories warning that the high humidity creates conditions conducive to mold growth and food spoilage. Residents are advised to take preventive measures at home, including dehumidification and proper food storage, while travelers should exercise caution on roads due to reduced visibility and potential waterlogging.

Meteorological Context

The 2026 plum rain season is driven by an adjustment in atmospheric circulation, with the Western Pacific subtropical high strengthening and extending westward and northward. Its ridge line is currently positioned at approximately 21°N. Three moisture transport channels — from the Pacific Ocean, the East China Sea, and the Bay of Bengal — are converging over eastern China, bringing abundant precipitation to the region.

The plum rain season typically lasts about 21 days in Shanghai. In 2024, the city exited the season on July 4, transitioning directly to high-temperature summer weather. Meteorologists will be monitoring whether the 2026 season follows a similar pattern or deviates from historical norms.

What to Watch For

As the rain band continues to oscillate over the middle-lower Yangtze River region, residents and authorities alike will be watching for potential urban waterlogging in low-lying areas, the effectiveness of Shanghai’s drainage systems, and whether the total precipitation and duration of the 2026 plum rain season align with or diverge from historical averages. The combination of the Dragon Boat Festival travel rush and heavy rainfall will also test the city’s transportation infrastructure and emergency response systems.