if you're interested, here is a site with quite a bit of information pertaining to the various factors when it comes to thawing. there's some technical stuff here, but this is mainly covering
ground conditions (moisture content of the ground).
http://www.hydrol-earth-syst-sci-discuss.net/7/33/2010/hessd-7-33-2010.pdf
i know the farmers almanac and seed packages might give the best times of the year (spring) for the planting of various seed, but in general, that happens well after the frost is gone from the ground since the presence or the possibility of frost will kill a lot of new/young plants.
the actual "thaw" dates will vary from one place to the next and it's not unusual for colder weather to stick around longer than expected for any given area. nor is it unusual for an early thaw in any given area. it ALL depends on the weather patterns.
due to that
uncertainty, i highly doubt that you ever find a 100% reliable chart that will tell you the ground at "Location X" will be thawed out on such-and-such a date.
Mother Nature has and always will have the final say, but if the alanac and the tomato seeds say it's time to plant, then there's a pretty good chance that the thaw has already happened and you've already been MDing and digging for a month or so prior to that time, lol.