Category: Commentary

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Summary for June 2015

One of the most notable features of June was the minimal rainfall of 22.2mm, which is just 40% of the average for June and the fifth driest I have recorded since 1984. The wettest day was the 1st with 8.4mm, almost half the total. There were 22 dry days so it is not surprising, with the minimal rainfall and the warmth later in the month, that 107mm of moisture evaporated into the atmosphere.

The mean temperature was fractionally above the 31-year average. This figure masks the contrasting temperatures throughout the month. The first two weeks were mainly cool with maxima well below the average. For many days the winds from a northerly quarter brought cool air, only 14.2C on the 9th when the mean is 19.7C and a minimum of 3.4C on the morning of the 3rd. However, summer did arrive towards the end of the month with the last eight days in excess of 20C, the warmest being the 30th with a maximum of 28.6C, the hottest day since August 2013.

There were several evenings, late in the month, that were very warm with almost still conditions – ideal BBQ weather. Such must have been an evening when in 1953 Vita Sackville-West wrote “Sit out in the white garden … till 10pm planning improvements … A perfectly still, breathless evening, scented and warm.”

The total number of hours of strong sunshine was 168, 19% more than in June 2014. The 30th June not only brought a hot day but the highest daily total of strong sunshine being 15.74 hours. It is not surprising that the solar energy total was the highest since June 2010. UV levels were mainly in the high category but later in the month often rated very high.

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Summary for May and Spring 2015

MAY 2015
In 1802, Dorothy Wordsworth wrote “A very cold morning – hail and showers all day…. William tired himself with seeking an epithet for the cuckoo”.

Many of us will sympathize with William, as there have been several days in the last month when it has been very cool, accompanied by frequent showers. Small hail fell in the showers on the 19th and thunder was heard on the 3rd.

There were two days when during the majority of the day the thermometer did not rise above 10C, (15th and 19th), the 18th and 19th fared little better with maxima of 12C before late afternoon. However, the coldest day occurred on the 14th when a maximum of 8.5C was the best that was recorded before mid-afternoon. Comparing these days with the long-term average for May of 16.6C indicate how cool some days were during the past month.

The mean temperature for the month was 0.4C below the long-term average, principally due to the cold days as the mean minimum was just above the 31-year average. It was notable that there were no air frosts during the month although several ground frosts did occur. The very cool nights meant that many plants in gardens were not badly frosted but have been somewhat stunted in their early growth.

The frequent showers produced a total of 83.1mm, which is 139 per cent of the long-term average or plus 47mm. It is interesting to note that the amount of moisture evaporating into the atmosphere from ground and water sources also from plant matter matched this total of 83mm.

Strong sunshine totalled 116 hours, which is some 70 hours less than the splendid April just past. The UV level was the lowest for May over the past 6 years, even though the levels were in the ‘High’ category towards the end of the month.

At times the past month has been a little depressing but not quite as bad as was written by Horace Walpole on 28th May 1774 – “We are almost freezing here in the midst of beautiful verdure with a profusion of blossoms and flowers: but I keep good fires, and seem to feel warm weather while I look through the window, for the way to insure summer in England, is to have it framed and glazed in a comfortable room”.

SPRING 2015
The mean temperature for the past three months was 0.2C above the long-term average, the warm April offsetting the cool May. Rainfall for the three months totalled 129mm, which is just 72 per cent compared with the 32-year average, a deficit of 50mm.

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Minimal rainfall and considerable evaporation

After 13 days this month the rainfall total is just 6.3mm when the average for April is 61.4mm. In contrast, the evaporation from the ground, plants and water surfaces is 28mm due to the rising temperatures and drying winds.

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