Nice winter weather a danger to kids?

The nice weather in the middle of January makes living in Boston easier. I am pondering if it is dangerous to some kids. I spent some times today on the porch and spied a neighbor's child- maybe 3 or 4 years old- out on their third-floor porch, atop two of those plastic porch chairs, hands on the railing, jumping up and down. If she'd gotten a little more enthusiastic she would've gone headfirst over the side.