I experienced something similar. A weather station about a mile away reported a low of 39 degrees yesterday. My own thermometer said 38 (about 30 minutes after the sun came up though).

Anyway I have frost damage on the top of my tomato plants and the pepper plants right next to them only had a leaf or two nipped. Half of my sweet potatoes plants across the yard are toast. Other very sensitive plants either have a few damaged leaves or are untouched. It's interesting to see the microclimates in my rather small yard.

I'm in Taylor Ranch so this is a very early first frost.

I've seen the same thing! But never with a reading of 47 degrees!

I've definitely seen frost damage on tender plants when my weather station read around 36 or so. It has always been on very calm, clear mornings, when heat is easily lost from the ground, especially over open, unprotected areas. My temperature gauge is nearer the house, at head level, instead of on the surface on my zucchini leaves, in which case I might expect to see something closer to 32 degrees on those mornings. Interesting stuff...