Shanghai officially entered summer on May 20 this year, as the daily average temperature was higher than 22 degrees Celsius for five straight days ending Saturday, the weather bureau said.

The mercury continued to climb, with a 27.9-degree high on Saturday and 31 degrees yesterday. Forecasters say the temperature in the city may reach a high of 33 degrees today and tomorrow. It will be sunny to cloudy, the Shanghai Meteorological Bureau said.

A spell of thunderstorms is expected to hit the city from late tomorrow to early Wednesday, when the temperature is tipped to plunge by eight degrees.

However, it is expected to rise again, with maximum temperatures above 30 degrees from Friday.

The arrival of summer has happened at a similar time to recent years, but earlier than the long-term average starting date. From 2005, the city has stepped into summer during the last 10 days of May, but summer traditionally starts in the first or second 10-day period of June.

Last year's summer arrived on May 13, which was the earliest since city temperatures were first recorded in 1873, according to the bureau.

The season also tends to be longer now.

In 2006, the city had a total of five months of summer weather - the longest summer in recent history.

(Shanghai Daily May 26, 2008)