It came from the OLD DG!
I finally realized that I got my "90-50-10% / 36-32-28 'F" table from the old DG website.
I got totally lost (again) among all the different NOAA pages. I think the best use I got out of them was just browsing by hand through daily highs and lows. I had some high-level stats like the USDA Hardiness Zone, but looking at the past detailed data showed me that winters went BELOW my USDA minimum in almost HALF of all years ... then I remembered that averages work that way. That's why I like the "90%" frost dates better than the "50%" frost dates.
>> Averaging the temps over several years skews the data significantly. Also, averaging the temps over the whole month also distorts the information.
Totally. I agree. Further, different kinds of averages confuse me. Like "daily extremes, averaged", or "extremes OF the daily average temperature".
>> The lows and highs do not reflect what temps I have experienced up here.
Is your area mountainous? I know that elevation and exposure can have a bigger effect than latitude. But also, for any kind of averaged statistic, each day or year will vary around that average, sometimes with a wide dispersion. But if your lows are USUALLY lower and your highs are USUALLY higher, than the stats are not describing YOUR location.
Someone living on a mountain (or maybe it was in a valley) mentioned that she couldn't use any of the NOAA stations to describe her yard. I think what she found was the Weather Underground, where many private people have stations that report data to some central database. She found someone fairly local whose station was located in a microclimate that was closer to hers than any of the NOAA stations were.
The fact that tables of Koppen Climate Zones by county have to put multiple - like 3-5 - zones into some counties show that weather may vary more from some blocks to some blocks than from some states to other states.
Here are some links I collected back in 2013:
http://garden.org/blogs/entry/...
Here is a list of every county in the USA, by state, naming all the Koppen Climate Zones that can be found within that one county, and what % of the area of the county has that Koppen Climate Zone:
http://koeppen-geiger.vu-wien....
Weather Underground weather history:
https://www.wunderground.com/h...
Like politics, weather is local. Averages and other statistics might not be useful unless you find
exactly the right statistic, and it is targeted at a useful geographic location.
