I note that the new climate zone map has put Spokane, Washington solidly in
Zone 6 (formerly Zone 5), along with most all of Eastern and Central Washington
north to the Canadian border. Now, just last week during thecold spell, our
official low in Spokane was somewhere around -19 or -20degrees F., and Deer
Park, about 20 miles to the north of us, was down to atleast -25 F. I'm sure
that those people just to the north of us will be comforted to know that they
are now in Zone 6, and can expect a maximum low of -10 F. BRBR

I'm afraid you have misunderstood the USDA standards for the climate zones. The
climate zone records the AVERAGE winter low temperature. If the lowest
temperature one year is -20 and the lowest temperature the next year is zero,
you have an average minimum temperature of -10.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)