When it is below 0 C, certainly. The outdoors can be awfully peaceful when everyone else is hiding out indoors.

When it is below 0 F, eInk doesn't fare very well. I have read outdoors under such conditions, which is how I know that. I have also used LCD based devices to read outdoors under such conditions, just so that I could read for extended periods. It actually isn't so bad if you're bundled up properly and have a device with physical buttons for turning pages. (Touch screens and gloves don't work very well.)