With the temperature dropping and the winds picking up it is important to keep an eye on your favorite 4 legged friend. While a lot of dogs don't mind the cold and even love to play in the snow they can still suffer from hypothermia just like people. So, it's important to adjust their outside activities accordingly as the temperatures drop. Today in Chicago it is -11 degrees and that's not even counting the windchill so when temperatures are that cold walks should be for utility purposes only.
However for more normal conditions a mostly healthy medium and large sized dogs can be outside for about 30 minutes as long as the temperature is above 20 degrees, and small dogs can be outside for 15-20 minutes. Any temperature below 0 should be thought of as very dangerous for any period of time so walks should be for bathroom breaks only!