Where I am, the temperature is expected to plummet to 9 degrees overnight, and that's going to be about the high for tomorrow. Tuesday it may rise to 14 degrees.
At the moment, it's not that cold yet, but it's quite windy, so with the wind chill it feels in the low 20's. My puppy insisted on going out, even though I've been trying to get him to use a Wee Wee pad instead. As soon as we got outside, he did what your dogs did, he immediately turned around and ran inside--without doing what we went out for. Tomorrow, with the wind chill it will feel like zero or below, and there is no way I'm taking him out, no matter how much he insists. I have no idea why he's suddenly averse to using a Wee Wee pad, but I think we're in for two difficult days.
51 degrees sounds balmy to me.