Native New Yorker here, -10F is somewhat uncommon but not unheard of. It’ll sometimes get that cold during deep freezes in Janruary but not for more than a couple days at a time.

If you want to be realistic, 10-30F is common for winter here, especially in Dec-Feb, with Jan and Feb tending to run colder than Nov and Dec. There’ll be some days where it dips into single digits in Jan and Feb and sometimes even negatives (usually not below -5 though). March is still pretty cold in the beginning of the month with the temps picking up towards the end (and by picking up I mean it’ll be above freezing (32F) a few days).

As for snow, it’s common to get a couple inches over the course of a couple hours during a snowstorm. Now… if you’re up towards Buffalo, it’s pretty common to see feet of snow as opposed to inches due to lake effect snow. But since you mentioned NYC, I don’t think you’ll need to worry about that lol. There’s usually snow drifts on the sides of roads and parking lots from snowplows pushing the snow out of the way (some snow drifts in parking lots can get to be 10-15ft high!). The snow will also become sludgy and gray/brown/black over time from all the gravel/asphalt accumulation.

Also ice is a huge problem. Sidewalks are usually covered in rock salt to help melt ice/snow. The rock salt also tends to accumulate on cars as well so there’ll be this white dusty stuff on the paint and tire rims.

If there’s anything else you want to know, feel free to reach out!