Rare cold air rushes in in the middle of summer, Hanoi is surprisingly cool
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While the people of the Capital were struggling to endure the scorching hot days of early June, a cold wave suddenly arrived from the evening of June 8, bringing widespread heavy rain and a sharp drop in temperature – a phenomenon considered by meteorologists to be the rarest in more than a decade.
This is the first cold wave that has appeared in June since 2014, or after 12 years, pouring down right before the 2026 high school graduation exam, cooling the heat and causing the weather to have many unusual fluctuations.
Long-term statistics show that this is not an unprecedented phenomenon, but is becoming increasingly rare over time. From 1979 to 2025, there have been 25 cold air waves in June, an average of 0.53 waves/year. However, from 1991 to present, the number of cold air waves in June has decreased significantly, to only 7 waves, an average of 0.2 waves/year, and from 2014 to 2025 there will be no cold air waves in June.
According to the National Center for Hydrometeorological Forecasting, on June 9, 2026, a wave of cold air compressing a low pressure trough flooded our country, causing widespread heavy rain in the North, ending the intense heat wave, the temperature in the capital Hanoi dropped sharply to below 30 degrees Celsius. The meteorological agency issued a warning about extremely high intensity rains, exceeding the threshold of 100mm in just 3 hours.
Due to the influence of cold air compressing the low pressure trough, from the night of June 8 to the night of June 9, the Northwestern region and northern Phu Tho had heavy to very heavy rain with a common rainfall of 80–160mm, locally in some places over 250mm; Thanh Hoa and Nghe An have moderate to heavy rain with rainfall of 50–100mm, locally over 150mm.
This weather system causes a high risk of flash floods and landslides in the northern mountainous provinces. People in highland localities are advised to monitor developments and proactively evacuate when necessary.
This unusual meteorological event coincides with a sensitive time of the school year. The meteorological agency warns candidates and parents to closely monitor the local weather situation, especially in areas forecast to have localized heavy rain in the evening, to proactively plan to travel to the test site safely and prepare appropriate clothing such as raincoats and umbrellas.
Despite the inconvenience, many Hanoians welcomed this unseasonal cold spell as a rare relief from the suffocating heat typical of the Northern summer — even if only for a few short days.
