Category: Commentary

Thursday saw the thermometer soar during the morning before a build up of cloud after midday halted the rise at 13.35 with a maximum of 30.4C, which was 8.1C above the 34-year average. The thermometer hovered around 30C for most of the afternoon. The previous record of 34.5C was set in July 2006.

The afternoon of Thursday saw strong gusts of wind from the south as the air became less stable with localised storms moving north to the west and east of Marlborough.

A very mild night followed with minimum of 14.9C, which was 3.1C above average.

Friday dawned with strong sunshine, after the clearance of cloud near the horizon, that boosted the temperature to 20.3C at 08.00.

A change in the weather is approaching as the barometric pressure has been dropping and at 08.00 is at its lowest this month.

Update at 16.00: maximum temperature of 28.0C at 15.04, down 2C on the Thursday peak but 5.3C above average. Less heat due to increased levels of cloud and thus reduced sunshine.

Wednesday brought a day with 11.6 hours of sunshine and Very High UV that lifted the temperature slightly higher than recorded on Tuesday with a maximum of 27.8C, which was 5.5C above the 34-year July average.

July to date:
Average maximum mean temperature: +5C
Rainfall: 4.9mm (average is 60.9mm)
Evaporation: equal to 108mm of rainfall
Sunshine: 220 hours

The average strong sunshine for July, over the past four years when this instrument was installed, is 109 hours. This instrument is triggered when the sun’s strength reaches 100w/sq.m.

Thursday arrived with, initially, broken cloud and occasional glimpses of strong sun that lifted the minimum of 11.7C, exactly average for July, to 16.8C at 08.00.

Update at 11.00: temperature just reached 28.0C, already beating highs of last two days, which usually occur mid to late afternoon. Mean maximum is 22.25C

11.00: 28.0C
11.30: 28.6C
12.00: 28.8C
12.30: 29.2C
13.00: 29.7C
13.00: 30.3C
13.35: 30.4C – the hottest day this month/ year
14.00: 30.2C
14.30: 29.6C
16.00: 29.9C

These temperatures are from instruments well up my garden on the outskirts of Marlborough. Instruments within an urban environment where there are numerous buildings, much paved concrete and tarmac surfaces also not in the shade from direct sunshine or shaded from solar energy, will indicate higher temperatures.

Tuesday brought another hot day with 9.42 hours of strong sunshine and a maximum of 27.7C at 15.34, almost 3C down on Monday’s peak but still 5.4C above average.

No day in July has seen the maximum fall below the 34-year July average of 22.25C.

My station is positioned on the outskirts of Marlborough, well up the garden and the furtherest away from any building and paved area. Therefore any instrument in the town closer to buildings of next to paved/tarmac areas that soak up the heat will give a higher daily reading. Also, although thermometers might be in the shade, professional instruments are all shaded from solar radiation to get as accurate an ambient temperature as possible and as close to Meteorological standards that can be obtained.

Overnight the minimum of 13.8C was recorded at 05.54, just after the sun rose. A short while later variable cloud obscured the sun but well before 8am the sun was coming through strongly and by 08.00 the temperature had risen to 18.0C.

Update at 17.18: maximum temperature of 27.8C reached at 17.15 with humidity exceptionally low currently reading just 33% in very light south westerly air of 5mph.

Monday saw the thermometer soar to 30.3C making it the hottest day since 21st June 2017 and 8C above the 34-year average.

The total hours of strong sunshine was the highest for a week with 11.25 hours.

There followed a much cooler night with a minimum of 12.3C, just above average.

By 08.00 on Tuesday the thermometer had already risen to 19.5C under the effect of one hour of intermittent strong sunshine.

The Meteorological Office class a day as dry if any precipitation is less than 1mm. Since 30th May we have had 49 dry days out of the 54 period.

June rainfall of 5.3mm BUT evaporation equivalent to 110mm of rainfall
July rainfall of 4.9mm BUT evaporation equivalent to 95mm of rainfall

Update at 17.20: maximum lower today at 27.7C, being 2.6C down on Monday’s peak due to variable cloud and reduced hours of strong sunshine. However, the peak today was still 5.4C above the 34-year July average.

Sunday saw the thermometer soar back up to 29.3C, being 7C above the 34-year July average and 3C above the peak on Saturday. This was the result of much blue sky and the resultant sunshine totalling 7.36 hours and Very High UV levels.

The change in wind direction also played a part, yesterday coming from the south west, a warmer direction than previously, which also increased the humidity level.

A mild night followed with the thermometer not falling below 15.7C, which was 4C above the average and the warmest night since 19th July 2017.

Monday arrived with thick fog limiting visibility to 200m that slowly began to evaporate so that by 08.00, when readings were taken, had improved to over 1,500m and a temperature that had risen to 18.2C.

The rain total for July still stands at 4.9mm when the average is 60.9mm. The other half of the story in this heatwave is that the equivalent of 95mm of rainfall has evaporated into the atmosphere from ground sources and plant life.

Update at 14.40: the thermometer has already passed the maximum set on Sunday with a peak of 29.5C at 14.38.

at 15.36: maximum of 30.3C being hottest day since 21st June 2017 (32.2C).