I agree - no system I know of can accurately describe the micro climates in an area where the elevation changes rapidly.
Someone COULD (in theory) apply the Koppen statistics to a detailed set of weather records for one part of one backyard (if you had those records). Then you could classify that part o that yard as one of the Koppen zones
>> The other thing not addressed is how our climate seesaws from year to year.
True! Like USDA Hardiness Zones, anything anyone says can only describe the past. Next year might be average, hotter, dryer, colder or wetter. Or all of the above, unseasonably!
Well, Koppen handles that like USDA Hardiness - by using records from a span of years. Each sub-category has limits defined by statistics. I don't know over how many years they average things, or the real statistical formulas ... this list is just a shorthand of the factors Koppen uses.
MAP = mean annual precipitation,
MAT = mean annual temperature,
Thot = temperature of the hottest month,
Tcold = temperature of the coldest month,
Tmon10 = number of months where the temperature is above 10,
Pdry = precipitation of the driest month,
Psdry = precipitation of the driest month in summer,
Pwdry = precipitation of the driest month in winter,
Pswet = precipitation of the wettest month in summer,
Pwwet = precipitation of the wettest month in winter,
Pthreshold = varies according to the following rules (blahblahblah)
Thanks for motivating me to look harder! I found this site:
and it says things like:
>> "The Köppen system classifies a location’s climate mainly using annual and
monthly averages of temperature and precipitation."
The following sound like they were intended to apply to MOST climate systems in use, not just Koppen:
>> "The classical length of record to determine the climate for any particular place is 30 years,"
>> "The "normals" are computed once every 10 years which helps to smooth out year-to-year variations. ... So, when you hear what the normal high and low temperature for your location, for example, they come from these 30-year averages."
It might mean that all the Koppen numbers are like "the hottest X in the last 30 years
". I was thinking they would use something like a 90% rule: like "a temperature which fewer than 10% of months exceed". If something occurs once in one year out of 30, that's 3.3%. Maybe that is their statistical rule.
That site also has a detailed list of what the Secondary Köppen Climate Categories mean, in English, instead of in math/statistical terms.