We have decided to put our plants out next weekend, since we still feel it is a bit early for where we are located. Plus, the full moon is only a few weeks away. At the Sandy River Farmers Market, I heard another farmer say "Full moon is on June 7th, we'll probably get a frost around then". When I first started farming I would hear it all of the time! I didn't understand, but it truly did seem to be that when the moon was full, it was colder. What is that all about anyway? So I decided to look into it.
I found many articles on the subject, but none scientific. Apparently, people believe that the heat of the full moon evaporates the clouds in the upper atmosphere. When those clouds have disappeared, there is no cover in the upper atmosphere to hold in the heat of the lower atmosphere, leaving us with colder nights down here on earth. I just don't believe this hypothesis. I could find nothing to back it up.
The closest I got to a scientific paper was on the MOFGA website: http://www.mofga.org/mofga/other/mofgs05f.html. By comparing the full moon cycle to temperature records from Houlton ME over the last 38 years, Mitch Lansky found that between May 18th and September 20th (the official growing season for Houlton), "only 26 out of the 232 days (11.2%) of full moons plus one day on either side coincided with frosts. The same period had 267 frosts out of 2280 days, so the chance of a frost on any day was 11.7 percent. Thus the coincidence of frosts with full moons seems to be random."
All of the other information that I read said the same thing. There really was no correlation between frost and a full moon. You know, I think that I will keep that to myself the next time Gramp says "full moon tonight, there will probably be a frost". Did he hear that from his father? Probably, he was a farmer on the same land that we are on now. Why spoil a perfectly harmless thing?