YESTERDAY was the hottest day of the year, a scorching 35.4 degrees Celsius at the Xujiahui weather station, according to the Shanghai Meteorological Bureau.

The bureau issued this year's first yellow heat-wave alert at 2:05pm yesterday. Most of the city's northwestern areas saw the mercury rise to 35 degrees and Songjiang District recorded the highest temperature — 35.6 degrees.

The weather bureau released another two yellow alerts for lightning and gales at 5:27pm yesterday, predicting evening thundershowers.