HTW #83: September is Baby Safety Month! - A baby should NEVER be left alone in a car, even with the window slightly open and even if it feels cool outside! Heat is much more dangerous to babies than adults. If you see an unattended child in a car, dial 911 immediately.
For more information, check out --- http://www.safekids.org/safety-basics/babies/on-the-way/heat-stroke-prevention.html