January is an excellent time of year to visit India. Whilst daytime temperatures in Himachal Pradesh, in the north of the country, will be cold and can drop below 10°C; further south the mercury rises and temperatures of 30°C are typical in the southern states of Goa and Kerala. There is little chance of rainfall throughout the country during January.
If you're planning a January trip to Shimla and elsewhere in India’s far north you'll need to pack plenty of warm clothing. High altitude places like Shimla, Dharamsala, Manali and Srinagar will be blanketed in a covering of snow with temperatures below 10°C. Lower altitude spots like Rishikesh are a little warmer, but you'll still need to pack warm clothing.
January is one of the most popular months of the year to visit Kerala, Goa and the rest of southern India. Typically the days are hot without being too hot and there's plenty of sunshine in cloudless skies. Along the many miles of lush coastline, you'll be unlucky if you encounter rain. Temperatures in the hill stations of the Western Ghats are chilly at night so pack a fleece or two if you plan to visit them.
If you're planning a January trip to Mumbai, Nagpur and the rest of central India you should experience pleasantly hot daytime temperatures, perfect for sightseeing. Night times and early mornings in the national parks can be chilly so pack some warm clothing if you’re planning on wildlife spotting. There's no need to take waterproofs - rain in January is very rare indeed.
If you're planning a trip to Rajasthan and the Golden Triangle sites of Delhi, Agra and Jaipur in January you'll encounter pleasantly warm temperatures in the daytime perfect for sightseeing. Night times and early mornings can be chilly so pack some warm clothing. Chances are you won't need a brolly as rain in the north during January is a rarity.