Hello and welcome to the forum!
Let's first identify the different seasons in Himachal Pradesh:
- Winter Season which is from October to February.
- Summer Season which is from March to June.
- Monsoon Season which is from July to September.
Now, let's discuss the winter season in Himachal Pradesh. It is usually December and January that receive the highest rainfall in the state. During the winter season, it's not unusual to find all kinds of snow activity like skiing, snow boarding and tobogganing. Temperatures vary between 0°C to 15°C, sometimes even lower. Higher altitude places like Manali, Shimla, Kufri and Narkanda receive greater snowfall due to their location. Regions like Keylong and Rohtang remain frozen all year round as well. This is one of the peak seasons of the state as well. This is the best season for adventure lovers.
On to the summer season, another peak season as people seek comfort and coolness in Himachal Pradesh. Temperatures range between 22°C and 37°C. Water sports can be done during this time. This is probably the busiest time of the state as tourists all over the country and the world flock to the region.
Monsoon season is next which can be quite dangerous as the roads are blocked by landslides. Dalhousie receives the greatest rainfall in the state. However, the lush greenery in the monsoon season can be quite captivating. Spiti, Tabo, Kinnaur, Dalhousie and Mcleodganj are probably the best destinations during the rainy season. But since it can be dangerous, plan accordingly. Not many tourists brave the monsoon season as well so you can get great discounts. You can plan your trip just after the monsoon season and before winter season starts. Check the weather and news reports about the current happenings in the region though.
So there you go... Summer season could be the most crowded time. Book in advance so you can have accommodations during that time.
I hope this helps!