Umborne Weather for May 2013
May 2013 concluded the three cold months that have
made up the ‘Spring’ Season this year. Even if you applied advanced
mathematics: degree days of temperature above 6C; the point when grass
growth starts: light intensity and duration and the study of plants
flowering and migrating birds, it is difficult to be really precise.
However, I should think that by the end of May, the Season was about
three weeks behind the norm.
The month started with a frost, -1.1C, the coldest of
four air frosts. Not unusual in itself: we had have colder nights in
the middle of May in 2010, and especially in 1996, which was the last
time we had such a cold overall month. Light winds and sunny days are a
recipe for cold nights in the valley, but 20C was reached for the first
time this year on May 2nd. Last year, this figure was reached on March
24th and then surpassed on the five subsequent afternoons, in what has
proven to be the last warmer than average month I have recorded. It took
until May 31st this year to reach 20C again, striding easily past the
post to reach 24C. Whilst this figure is much lower than last year’s
remarkable high of 29C, we should remember that in 2011 the figure of
20C was never reached.
After a week of generally dry, seasonal weather,
despite more chilly nights, the weather turned unsettled, with some rain
being recorded on ten of the next eleven days. This period was cold too,
with the 14th being a particularly dismal day, with a maximum
temperature of just 11C, and a total rainfall of 18.8mm, surpassing the
7th and 27th which gave values of more than 10mm. These three days
contributed just over 50mm of the month’s average overall total of
67.4mm. There were thirteen days with measurable rainfall.
After this wet spell conditions became generally less
cold, but there were still some poor statistics, some of which would
have read worse was it not for the fact that my ‘day’ for readings runs
from 1000-1000 BST, so sometimes, the following morning has reached a
warmer temperature than all of the previous day. However, another
negative statistic was recorded with a minimum of -0.3C on 26th.
Whilst this was not a true airfrost, due to the fact that my minimum
thermometer reads ‘low’, it was nonetheless the latest Spring date
on which I have ever recorded a sub-zero night. This period led to three
rather unsettled days, before the weather turned fine and warmer at the
end of the month.
I do not have the actual figures to prove the
statistic which has been announced nationally; that is that this Spring
has been the coldest since 1962. However, I was recording readings in
those days and I well remember that after a fairly average January,
February turned colder towards its end, and led into a March, whose
average temperature was about 3.5C below average, an April which came
out more than 1C below average, and a May, 2C below. The temperature
comparisons are very much in line with 2013. Fortunately, the rainfall
figures in 1962 were somewhat different to the totals of this year, with
February being very dry (7mm in Bournemouth), March & April around 70%
of average, and May about 140%.
Why my concern? Nobody in the weather world has dared
to mention the subsequent winter in the same breath, but many of us will
remember the 1962-1963 winter as the severest ever recorded. So, if you
want to get depressed, take note of how 1962 developed and see how
things progress in 2013. A dry, sunny, cool June; a dry, dull and cool
July endorsed by August. Autumn started cool and wet if reasonably
sunny; a benign, sunny, dry October with average temperatures, and an
early onset of winter in November. We know that our weather patterns
are chaotic, and that any repetition is probably sheer coincidence, but
it should be remembered that a cold Spring Season means that our
surrounding seas become colder than usual. At present this figure is
about 2C below normal. As we are an island, all air streams have to
cross water to reach us, and the result is that the wind feels cold
regardless of the direction from which it blows. So, we need a ‘good’
summer to help warm the seas and hopefully break us out of the pattern
that has become established.
My stats. for March-May 2013: Average temperature 7.1C with 34 air frosts, and total rainfall of 221.4mm from 43 rain days.
Peter at Pottlelake