Yeah cold temps are a double whammy, both in decreased battery efficiency and the need to heat yourself.
You can mitigate things, though. Regardless of what kind of heating system, just... not turning it on except to defrost windows, and instead making use of the heated seats, steering wheel etc makes a big difference.
Speed of driving makes a massive difference regardless, the slower the better.
Also, if you are doing a trip where the start and end are at different elevations... bear in mind that you will go high to low with no range issues at all, but the reverse will be true when going the other way.
If there are a few charging points along the route you'd be fine. Buying a car that just about works now is risky as it may end up not doing so as the battery degrades.
And, you really don't want to be regularly going below 20% (?) of charge, or charging to above 90% (?) as this will speed battery degradation.
So, if you have a car that's rated for 150 miles and want to drive 100 without recharging on the way, you're going to be cutting it fine if it's cold, uphill, you have the heater on, and you're trying to not fully charge/discharge the battery...