That can get long and tiring if you aren't flying!
There are direct flights but no direct trains for this journey. Bengaluru (Karnataka) to Srinagar (Jammu And Kashmir) distance is 2970 km and you can get there by flight in just over 5 hours and 5 minutes or by train + flight fares starting from ₹ 3458.
The temperatures at this time of the day are in a comfortable range.