Shanghai, Jun 29 (IANS): Shanghai has so far issued four yellow alerts for abnormally high temperatures this year, though it has entered the annual rainy season, known as "plum rain season" in China.

On Thursday morning, the city's major meteorological observatory issued this year's fourth yellow alert for high temperatures, the third-highest alert in China's four-tier colour-coded weather warning system, reports Xinhua news agency.

Shanghai is experiencing a rapid temperature rise and is expected to encounter a maximum daily temperature of over 35 degrees Celcius.

On June 17, Shanghai entered the annual plum rain season earlier than usual.

After two rounds of heavy rainfalls, the city began undergoing a temperature rise.

On Wednesday, the Xujiahui weather station in the city proper reported that its maximum temperature reached 35.8 degrees Celsius, making it Shanghai's hottest day this year.

Usually, it is rare to see such high-temperature days during the city's rainy season in summer.

However, Shanghai has recorded more and more hot days since the late 1980s.

Over the past decade, it experiences about two high-temperature days every plum rain season on average, said the city's weather authorities.

Shanghai will still be affected by the rainy season, as starting from Thursday, the city will go through a two-day strong convective weather, with lightning, thunderstorms, and even hail in some parts.