UV highest for a year on Monday

Monday brought 10.8 hours of sunshine and the highest UV level, with a reading of 9.7 just after 13.00, since 20th June 2018. As a result the thermometer steadily rose to a maximum of 21.C at 14.54, which was 1.6C below the 35-year average. The temperature was modified by a brisk wind that had backed from the west into the north west – a cooler direction.

As a matter of interest, although June is the mid-summer month, the average temperature in July is 2.5C above that for June as the land slowly absorbs heat from the sun with reduced loss by night.

A dry start to the month with 3.8mm of equivalent rainfall lost through evaporation from ground sources and plant life. At the end of June, during the very hot few days, we were losing in excess of 5mm every day.

A cool night was to follow as the thermometer fell away to 7.4C at 5.24, just after dawn. This was the coolest night since 22nd June and 4.4C below the 35-year average.

Tuesday arrived with strong sunshine that lifted the temperature to 13.8C at 08.00.

The barometric pressure has been rising steadily for the past twenty-four hours and as a result there is only variable cloud and mainly clear skies at night that allows heat from the land to radiate into the atmosphere without a cloud duvet.

June 2019 Review

June was a disappointing summer month, wetter than average and below average solar energy, all due to a depression that was reluctant to depart our shores as it slowly revolved anticlockwise around the UK for many days.

The month started well with two days of above average maxima, 25.6C and 22.3C on the 1st and 2nd but thereafter it went downhill with 18 consecutive days of below average maxima. Not until the 22nd did some warmth return, as an anticyclone eased in from the west, but only briefly, when the temperatures began to rise well above average with a maximum of 31.8C on the 29th. This peak was 11.6C above average and the warmest June day since 2017 (32.2C), all thanks to a blast of hot air from the Sahara Desert.

On the downside the thermometer only rose to 11.4C on the 11th, almost 9C below average with the previous very cool night down to 4.5C (-5.6C).

Although we had an average number of wet days, (rainfall equal to or greater than 1mm) the precipitation was 133% of the 35-year average or plus 17.6mm. The main contributor to the monthly total was a very wet day on the 10th when 25.1mm of rainfall was recorded making it the wettest day since May 2018 when 31.9mm fell.

The amount of equivalent rainfall lost to the atmosphere, due to evaporation from ground sources and plant life, amounted to 85.7mm, being 15mm above the rainfall in what was a wet month.

It was not surprising to find the UV level for the month was the lowest since 2012 and solar energy only 91% of the 9-year average.

On the bright side there were no days with fog, hail or frost (2 days in 1991) and we missed the torrential downpours that some areas of the country endured. A city in Mexico on Sunday suffered from a fall of ice pellets 2 metres deep when the normal temperature is around 30C. Marlborough is fortunate in that we have for a long time not suffered from the extremes of weather that other areas of our country have experienced.