WINTER TEMPERATURE:
The winter, or more accurately the non-growing season has been divided into
three separate periods: 1) November and December 2) January and February,
3) March.
The long-term, thirty-year average mean temperatures for the south coastal
station of Agassiz and the southern interior station of Vernon Coldstream
show very similar patterns (graphs #1-5). It is evident that in the
pre-winter and early winter period, there has been very little change over
the more than one hundred yearsof record; pre-winter, if anything, there
has been a slight cooling over the most recent fifteen years. January and
February, conversely, have shown a gradual trend to milder conditions in
both localities. The overall temperature increase has amounted to over two
degrees Celsius in the southern interior and approximately one-and-a-half
degrees on the south coast at Agassiz Canadian Department of Agriculture
(C.D.A.). A trend to milder conditions has also been evident also in the
month of March with a warming of approximately one-and-a-half degrees at
both the interior and coastal sites within the past forty to fifty years.
Just how much of the warming is in response to the increase in greenhouse
gases is extremely difficult to discern. This is the main goal of this
website: to determine the likely causes for climate change to date and that
of the future. Most scientists believe that the PDO has been in the warm
phase until recently. During that time, as shown in (graphs #1-4), both the
coastal and southern interior have been significantly milder through the
winter months, with the exception of the pre-winter month of November and
the early winter month of December. The upper air circulation often
responding to the PDO conditions, tends to bring milder air to the Pacific
coast and is as such one important factor.

This is concluded mostly on the basis of an examination of the early warm
period (1925-1947), as compared to both the earliest (1892-1924) and the
later (1948-1975) cold phases of the PDO. The months of November and
December are marginally milder in the trough or warm phase. January through
March on the other hand, have been milder by over one degree Celsius at
Vernon as compared to the early cold phase, and by over-a-half degree
Celsius milder than the later cold phase. Agassiz also has been milder in
the earliest warm phase as compared to the cold phases in all months from
November to March . Barkerville, in B.C.'s central interior, did not show
the temperature differences observed further to the south through the cold
stages and the earliest warm stage, this may be due to different upper air
circulation patterns further north in the British Columbia. At least based
upon the temperature analysis done here, the most recent warm or
trough phase of the PDO has shown the mildest temperatures January through
to March for Agassiz, Vernon, and Barkerville: milder even than the early
warm phase. A comparison of the two warm phases shows that the most recent
warm stage is over one-and-a-half degrees milder at Vernon for the months
January to March. At Agassiz, the warming has not been quite as great, more
in the range of 1.0 degree for January and February and just over 0.5
degrees for March. Barkerville has also been milder by approximately 1.0
degree Celsius in the latest warm phase, January to March as compared to
the early trough phase.

This suggests to me that something other than the PDO is involved.
Interestingly, there has been a consistent lack of warming in the
pre-winter and early winter months of November and December. Perhaps in the
early winter the upper air circulation has not evolved into the milder
pattern exhibited later in the winter. Contributing to the climate changes
may also have be some natural variability, perhaps in the form of a more
active sun. However, it does seem that at least recently, the increasing
concentrations of greenhouse gases in our atmosphere are overwhelming other
factors. Based upon the analysis done to date, I believe that winter
temperatures in the January to March portion of winter have warmed by 1.0
to as much as 1.5 degrees Celsius, primarily because of mans' influence.