I’ve heard that EVs are bad in cold weather. What should I keep in mind?

The first thing to keep in mind is that EV’s aren’t bad in cold weather. In some ways they are much better than ICE cars (said with irony, given that Internal Combustion Engine acronym). Cold weather certainly affects all cars, it’s just with an EV you can measure it more accurately and you don’t have that extra benefit of all the wasted heat energy from a gas engine.

There is no avoiding some range loss associated with cold weather, due to simple lithium-ion battery chemistry. That, plus the need to heat the cabin without burning fossil fuels and using that heat byproduct, will give you some range loss in colder climates. A good rule of thumb is expect 10% range loss for temperatures around 50F and 20% range loss for temperatures around freezing.  Maryland doesn’t typically see temperatures past that, but the colder it gets, the more range you’ll lose. Extreme heat would have a similar impact, although exact numbers are not available.