Shanghai has experienced its longest summer in 140 years, with the temperature on Monday Oct. 14?hitting 28 degrees Celsius, the Shanghai Meteorological Bureau said.

Monday was recorded as Shanghai's 157th summer day this year. Summer began on May 11.

The bureau declares the start of summer when the average temperature for five consecutive days is above 22 degrees Celsius.

The average number of summer days in Shanghai during the past 10 years was 134. 2006 and 2009 both recorded 156 summer days.

"But the temperature in Shanghai is expected to drop sharply on Tuesday, as a cold front is coming towards the city," said the bureau.

Downtown Shanghai is forecasted to be 14 degrees Celsius on Wednesday morning. The city is expected to enter meteorological autumn soon, according to the bureau.