Author: Eric Gilbert

During Friday advance cloud from the low pressure system approaching from the Atlantic was observed, occasionally obscuring the sun. Even so, the thermometer rose to 27.8C being 7.6C above the 39-year average and the fifth successive above heatwave threshold of 27C.

The past night was mild with the thermometer not sinking below 12.8C, which was 2.8C above the average.

Saturday after dawn revealed thin high cloud with clumps of thicker cloud that produced raindrops at 06.00 and 07.10 but not measurable. However a line of showers passed over the area at 08.00, from the southwest that will be measurable at the end of the day.

Thursday gave us the greatest solar energy this year, but it is almost the longest day, with wall to wall sunshine. As a result the thermometer reached 27.1C, being 6.9C above the 39-year average, and the fourth above 27C for the heatwave threshold.

The last night has been warm with a low of 12.3C, which was 2.1C above the average.

The loss again of over 5mm daily of equivalent rainfall was not surprising due to the heat and drying breeze. We have no lot 57.9mm of equivalent rainfall due to evaporation from ground sources and plant life when the rainfall has been just 14.8mm.

Friday revealed some high thin cloud that meant the sunshine was a little weaker. This is ahead of a depression edging in from the west and heralds a significant change in our weather for the next few days. The extreme heat will be no longer after today but replaced with lower temperatures and more cloud with the possibility of modest rainfall.

The temperature at 08.00 was 20.0C making it the warmest start to a day at that time since 12th August. The air movement is now from the east and likely to veer from the southeast, a direction not seen for a month.

A maximum of 27.6C was logged at 17.52 on Wednesday, therefore, Marlborough has experienced a meteorological heatwave as three consecutive days with maxima above the 27C threshold have occurred, namely 27.8C, 28.6C and 27.7C respectively. The peak of 29.8C was recorded on Saturday but not consecutive with the last three days.

The past night gave us a minimum just above the 39-year average (+0.6C) with a low of 10.7C.

Thursday arrived with strong sunshine again that lifted the temperature to 18.9C at 08.00.

The high pressure system stretching from Scandinavia to the UK has intensified by 3mb since yesterday, a pressure reading of 1020.8mb at 08.00 was the highest since Wednesday. This increase combined with a slight reposition has meant the breeze has backed a few more degrees from principally north yesterday to northeast today.

Although a maximum of 28.6C was recorded on Tuesday, Marlborough has not technically experienced a heatwave. The heatwave threshold for Wiltshire is 27C and for a heatwave to be declared there must be three consecutive days when the threshold is exceeded. We have now had two consecutive days when the peak exceeded 27C, that was 27.8C on Monday and 28.6C on Tuesday but Sunday only reached 25.1C. If the maximum today is above 27C, we will be experiencing a meteorological heatwave.

The loss of equivalent rainfall through evaporation reached 5.18mm on Tuesday. So far this month the total loss to the atmosphere is 48mmm compered to the rainfall of 14.8mm.

It was a cool night as the thermometer sank to 8.6C being 1.5C below the average.

Wednesday arrived with strong sunshine again. By 08.00 the thermometer had reached 15.3C and was rising steadily.

Update at 18.00: a maximum of 27.6C was logged at 17.52 today. Therefore, Marlborough has experienced a meteorological heatwave as three consecutive days with maxima above the 27C threshold have occurred, namely 27.8C, 28.6C and 27.7C respectively.

Monday saw the temperatures began to recover after the rain of previous days. The thermometer peaked at 27.8C being 7.5C above the 39-year average.

No rain fell in the past twenty-four hours, the storms were to the north of our area. The UV level just edged into the ‘Very High’ category.

The past night was mild with a low of 11.7C, being .6C above he average.

As the land begins to dry out after the rainfall the rate of evaporation has begun to climb again. The equivalent loss of rainfall through evaporation from ground sources and plant life now totals 43mm for June against the rainfall of 14.8mm.

Tuesday saw the sun begin to shine strongly shortly after it rose above the horizon lifting the thermometer to 19.5C at 08.00. The wind has veered into the northeast again, but light.

Update at 17.30. Although a maximum of 28.6C was recorded today, Marlborough is not technically experiencing a heatwave. The heatwave threshold for Wiltshire is 27C and for a heatwave to be declared there must be three consecutive days when the threshold is exceeded. We have now had two consecutive days when the peak exceeded 27C, 27.8C on Monday and 28.6C on Tuesday but Sunday only reached 25.1C. If the maximum tomorrow is above 27C, we will be experiencing a meteorological heatwave.