Indian Meteorological department has classified North India into two climatic zones viz. Himalayas and North Indian Plains.
North India has three distinct seasons viz. winter, summer, and the monsoon. Generally, the best time to visit North Indian plains is winter and the Himalayas in Summer when the weather there is pleasant.
Summer season in North India is from March to May followed by monsoon June to July. North Indian plains start heating up around February and iits temperature is around 35 degree C by April. By June monsoon rains start and humidity level rises. As the heat in Northern Plains is scorching, it is better to move towards Himalayan region to enjoy pleasant weather.
Monsoon brings respite from heat and August to September are pleasant. October and November are bit cooler but full bloom winter falls in Northern Plains in December to February which is a right season to tour North Indian Plains.