I don't think we got a frost at all. The lowest temp I've seen this morning was 36°. (predictions were for lows in the 20s, so much for weather forecasts!). After the sun came up there was no visible frost on rooftops or anything else.
I did cover my wintersown jugs with towels. I haven't looked at the seedlings yet but I don't expect any damage at all. Our 10 day forecast is for cooler temps than we've been having but lows around 40, with only Wednesday being 36°. We'll see. But these cooler temps aren't going to help sprout the rest of my wintersown seeds.
Karen