|Beside river Beas and the snow covered moutains in the backdrop|
The travel route we chose from Chennai was to take a train to Delhi (Nizamuddin Station) from Chennai Central. There are several train options, some of which may get you to Delhi sooner than 30hrs from departure. Manali is a further 15hrs travel (approx) from Delhi. There might be wiser travel options en route Chandigarh and others which you may opt depending on your budget.
The weather in Manali according to my I Phone was a max of 33 degrees and min of 13. Though one might assume that this is not really cool by hill station standards, the maximum temperature is witnessed only during daytime and temperature drop is evident between late evening and early morning hours. During winters there is heavy snow fall and several places might not be accessible. This makes summer and months extending up to September the ideal time to visit Manali.