LAST SPRING FREEZE

It is perhaps not surprising that the dates of the last spring freeze have
recently tended to be earlier recently, certainly, a part of the reason
does appear to be the fact that we have been in the warm phase of the
Pacific Decadal Oscillation. Also, there does seem to be a carry over
effect from the winter period into the spring. This is illustrated in the
last spring freeze dates, not only in the latest warm phase but also in the
earlier warm stage as wel (table #2).

It is difficult at this point to say with certainty what the cause(s) are
for the earlier spring freezes. Most certainly, it does appear that the
warm phase of the PDO does result in average spring freeze dates being
somewhat earlier. Also, there may be an influence of lowering snow packs on
the spring freeze dates-particularly recently. I base this conclusion upon
three stations examined which have tended to have earlier spring freezes
within the past fifteen years (table #3). It must be said however, that the
trend to earlier spring freezes may be a part of the natural variability in
the climate. Also, growing season temperatures within the past fifteen
years have been slightly warmer throughout the province. For now, judgment
as to cause(s) will have to wait until more information and analysis is
done.