on 26 May 1998. The lowest ever temperature ever recorded is at airport on 11 January 1967. The highest temperature ever recorded in Safdarjung is on 29 May 1944 & lowest recorded is on 16 January 1935. On January 8 2006 Delhi recorded minimum temperature of , the coldest in 70 years. On December 30 2019 Delhi recorded lowest maximum temp ever at at Safdarjung & at Mungeshpur. On January 1 2021 Delhi recorded temperature of , the coldest in 15 years. The annual mean temperature is ; monthly mean temperatures range from . The highest temperature recorded in July in Safdarjung, Palam, Ayanagar & Delhi Ridge are on 1 July 1931, on 5 July 1987, on 11 July 1982 & on 7 July 2009 respectively. The average annual rainfall is approximately according to 1961-2010 Long Period Average, most of which falls during the monsoon in July and August. But it was revised to according to 1971-2020 Long Period Average. The average date of the advent of monsoon winds in Delhi was 29 June but it was revised to 27 June in 2020. On January 2022 Palam broke all time high monthly rainfall at which is double it's previous record of in 1973. Air pollution According to the World Health Organization (WHO), Delhi was the most polluted city in the world in 2014. In 2016 WHO downgraded Delhi to eleventh-worst in the urban air quality database. According to one estimate, air pollution causes the death of about 10,500 people in Delhi every year. Air quality index of Delhi is generally moderate (101–200) level between January to September, and then it drastically deteriorates to Very Poor (301–400), Severe (401–500) or Hazardous (500+) levels in three months between October to December, due to various factors including stubble burning, fire crackers burning during Diwali and cold weather. During 2013–14, peak levels of fine particulate matter (PM) in Delhi increased by about 44%, primarily due to high vehicular and industrial emissions, construction work and crop burning in adjoining states. It has the highest level of the airborne particulate matter, PM2.5 considered most harmful to health, with 153 micrograms. Rising air pollution level has significantly increased lung-related ailments (especially asthma and lung cancer) among Delhi's children and women. The dense smog and haze in Delhi during winter results in major air and rail traffic disruptions every year. According to Indian meteorologists, the average maximum temperature