The range chart here might help.viewtopic.php?t=4295
It would also help to know whether you're talking about a new model or a used 2013-2015 Leaf. The SV and SL models have a heat pump which is a power saver for heat, especially when temperatures are above -5C or so.
With an older 24kWh Leaf, I would say your top range with moderate heat will be in the 70km area, but consult the chart with your data to be sure. What is your required range - and do you know whether workplace charging is available or an option?
2013 SL with Premium package - build date 5/13. 12 bar car with 53,000 miles and counting... Trying to nurse 12 bars to 60,000 miles and beyond if possible!
2014 Volt - 48,000+ miles