New Delhi is commonly classified as having a Köppen Cwa climate.
In the Köppen system, C indicates a temperate climate, w means the winter is dry, and a denotes a hot summer. The code therefore describes a humid-subtropical setting with a pronounced dry winter and very warm summers. Delhi’s summer monsoon supplies much of its annual rain, while winter is comparatively dry and often foggy.
The classification is a useful generalization rather than a perfect description of every part of the Delhi region. The city lies close to the boundary with BSh, the hot semi-arid steppe climate, because rainfall is relatively seasonal and dry conditions can be severe before the monsoon arrives. Different datasets, station locations, averaging periods, or boundary rules can therefore produce slightly different maps.
A common mix-up is BWh, which means hot desert, or Cfa, which is humid subtropical without a dry season. Delhi’s strongly seasonal rainfall is the reason the middle letter is w rather than f.