Shanghai recorded its hottest day of the year so far yesterday with temperatures reaching 32.6 degrees Celsius.

And today could be even hotter, the Shanghai Meteorological Bureau said, with temperatures reaching 33 degrees.

Park visitors enjoy the sunshine in Shanghai yesterday as temperatures soared to 32.6 degrees Celsius to make it the hottest day of the year so far.?[Shanghai Daily]

City forescasters said the lack of cloud and wind was responsible for the rising temperatures. The three days since Friday have all seen readings in excess of 30 degrees.

Zhu Jiehua, chief service officer with the bureau, said such high temperatures in early May were not uncommon. Conditions were similar in 2007, 2009 and last year.

There will be some respite from the heat tomorrow and on Wednesday when showers are expected to help bring temperatures down to between 24 and 27 degrees. It will be windy on Thursday, forecasters say, which will lower temperatures even further - to between 18 and 24 degrees.

Though the sun was shining yesterday, air quality in the city was said to be "lightly polluted" as a result of the lack of wind.

Friday saw similar conditions but air quality had improved to "good" the next day before dropping again in the evening.

The Shanghai Environmental Monitoring Center issued a warning yesterday morning, urging anyone with respiratory diseases or weak immunity to stay home.

The amount of PM10 and PM2.5 particles reached a peak between 9am and 10am yesterday. The PM2.5 density in Putuo District reached 190 micrograms per cubic meter at about 9am and 200 micrograms per cubic meter at Zhangjiang in the Pudong New Area about an hour later.

China's acceptable daily limit for PM2.5 is 75 micrograms.

Shanghai's PM2.5 density was above that figure from Saturday evening and for most of yesterday.

PM2.5 particles pose major health risks as they are small enough to lodge in the lungs and even enter the bloodstream.

Environmental officials said the pollution was caused by Shanghai's own pollutant sources, rather than particles from northern sandstorms blown in by the wind. But the sources weren't named.

Air quality today will be lightly polluted and good tomorrow, the center said.

Along with the rise in temperatures, the Shanghai Food and Drug Administration is warning local eateries and residents to take extra care during processing and cooking because of the increased risk of bacterial food poisoning in the heat.