Hmm .. that journey is surely more than just a weekend trip ?
There are direct trains but no direct flights for this journey. Chennai (Tamil Nadu) to Haridwar (Uttarakhand) distance is 1889 km and you can get there by flight + cab in just over 9 hours and 41 minutes or by train fares starting from ₹ 675.
The temperatures at this time of the day are in a comfortable range.