A powerful burst of summer storms struck Shanghai on Friday, leading the city's meteorological authorities to issue dual yellow alerts for heavy rain and lightning – a combination that signals heightened weather risk and the potential for significant urban impact.
At 3:19pm, the Shanghai Meteorological Bureau upgraded its rainstorm warning from blue to yellow – second lowest in a four-color system, following several hours of intensifying rainfall across the region. The yellow lightning alert, lowest in a three-tier-system which had been in place since early morning, remained active. Together, the two yellow warnings placed Shanghai under a rare and serious weather alert status, triggering immediate precautions citywide.
According to the forecast, districts, including Minhang, Songjiang, Jiading, Qingpu and Chongming as well as the Pudong New Area, could see hourly rainfall totals exceeding 50 millimeters over the next several hours. Such rainfall can quickly overwhelm drainage systems and lead to localized flooding, particularly in underpasses, low-lying roads and older neighborhoods with poor runoff infrastructure.
Yellow rain storm alert: Within the next six hours, one or both of the following conditions may occur or have already occurred and are likely to continue: Hourly rainfall of 50 millimeters or more, or total rainfall of 80mm or more within six hours.
Yellow lighting alert: a high likelihood of lightning activity within the next six hours, or that lightning has already occurred and may continue to affect the area.
In response to the upgraded alert, the city's flood control authorities initiated a Level III emergency response, calling on all affected districts to implement flood prevention and drainage measures. Authorities have warned the public to prepare for sudden downpours, reduce nonessential travel, and secure homes, balconies, and storefronts against water accumulation.
As evening set in, weather officials warned that scattered thunderstorms and additional heavy rain would remain likely through the night. Temperatures will stay around 33 degrees Celsius, but high humidity – hovering above 90 percent – will maintain a muggy, uncomfortable atmosphere, especially in areas without sufficient ventilation.
City workers and emergency crews have been deployed to monitor drainage points, manage traffic flow, and respond to waterlogging. Residents are advised to avoid flood-prone streets, refrain from outdoor construction or electrical work, and remain indoors during periods of thunder and lightning.
With both yellow rainstorm and lightning alerts active across most of the city, Shanghai is bracing for more instability in the hours ahead.
Officials continue to monitor the situation and emphasize the importance of staying informed through official weather bulletins and real-time updates.
Although the intense heat has temporarily eased, Shanghai is now facing 10 consecutive days of rain, accompanied by high humidity and a lingering muggy feeling.
Over the weekend and into next week, the city will be influenced by southeasterly and easterly airflows, bringing occasional clear skies but also a sharp increase in atmospheric moisture. Scattered showers and thunderstorms are expected, though they will occur with a degree of randomness.
Residents are advised to carry umbrellas at all times, as conditions may shift quickly. Daytime highs will remain between 33 and 34 degrees, and while the extreme heat may appear to have retreated, the high humidity will continue to make the air feel sticky and oppressive.
Level III (yellow) emergency response for flood and typhoon control