OK, it’s not ideal, but I have found a paper with some kind of average or “climatology” for freeze levels in the Northern Hemisphere. It’s at this link:
and has a map in meters. There are also seasonal maps and a standard deviation map.
The live version of the present freeze level map is as this link:
This map is the present state (measured in feet. I’ve not found a map in meters yet, so we get to ‘adjust’… ) and I’ve not found a map for “this month” or other averages. The ‘freeze level’ products seem to be mostly aimed at aviation and they care about “now” and “soon”, not averages of “back then”. A conversion chart for your convenience:
1000 meters is 3281 feet
2000 meters is 6562 feet
3000 meters is 9842 feet
4000 meters is 13123 feet
5000 meters is 16404 feet
As I read the pdf “paper” the monthly mean for January for North America (Figure 5) has a 2000 m line at about the border of Canada, a 3000 m line middle of the USA to about Georgia to San Francisco and the 4000 m line is down in Baja California to Orlando Florida.
I make that 6500 feet, 9800 feet, and 13,000 feet rounding down. So, when we look at this Freeze Level Map, is 6500 feet on the Canadian Border? Is 10,000 near Georgia? 13,000 feet in Orlando?
Uh, I’d make that a ‘No’…
And I’m afraid to ask what that Beige Blob is over the Great Lakes and New England… It seems to be ‘below the graph range’?…
It was a little better on 5 January 2011 when we first saw one of these graphs, but not by much: