The climate of Delhi is a monsoon-influenced humid subtropical (Köppen climate classification ''Cwa'') with high variation between summer and winter temperatures and precipitation. Delhi's version of a humid subtropical climate is markedly different from many other humid subtropical cities such as Sao Paulo, Tokyo and Brisbane in that the city features dust storms (something more commonly seen in a desert climate), has relatively dry winters and has a prolonged spell of very hot weather. Summers start in early April and peak in May, with average temperatures near 32 °C (90 °F), although occasional heat waves can result in highs close to 45 °C (114 °F) on some days. The monsoon starts in late June and lasts until mid-September, with about 797.3 mm (31.5 inches)[1] of rain. The average temperatures are around 29 °C (85 °F), although they can vary from around 25 °C (78 °F) on rainy days to 32 °C (90 °F) during dry spells. The monsoons recede in late September, and the post-monsoon season continues till late October, with average temperatures sliding from 29 °C (85 °F) to 21 °C (71 °F).

Winter starts in November and peaks in January, with average temperatures around 12–13 °C (54–55 °F). Although winters are generally mild, Delhi's proximity to the Himalayas results in cold waves. Delhi is notorious for its heavy fogs during the winter season. In December, reduced visibility leads to disruption of road, air and rail traffic.[2] They end in early February, and are followed by a short spring hill the onset of the summer.