Your tolerance to cold weather may vary but I find that if it's below 20 F it's too cold for me to walk outside even when bundled up properly.
If the weather is 30 F and the wind starts blowing then I never go outside in it and stay inside and use my treadmill for walking and exercise instead.
I can handle a little bit of cold weather as long as the wind is not blowing in my face but when the wind is blowing in my face it makes it so much colder on me.
Some people go out in negative degree weather and walk around or run for around 15 to 20 minutes which is okay as long as you're bundled up and dressed warmly but still you shouldn't stay out in the negative degree weather more than 20 minutes.
I find it much more enjoyable to walk, jog or run in warmer weather though than I do in cold weather.