Category: Commentary

The gardeners on Tuesday would have welcomed the twelve hours of almost continuous rain although those on half term break would not have appreciated the very wet and cool day. The precipitation was never very heavy thus no damage to crops. The rain and drizzle started just after 07.30 and ceased just before 22.00, amounting to 9.0mm, making it the wettest day since 26th February. The additional precipitation took the monthly rainfall to 23.6mm when the 41-year average is 60.4mm.

Not surprisingly, under the thick blanket of cloud and no sunshine, the day was cool with the maximum of 16.0C, logged at 14.01, being 1.3C below average, the first below average since the 15th, in fact there have only been five below maxima this month. Conversely, the cloud provided a duvet to keep in the warmth overnight thus the minimum of 12.2C, logged at 05.20 just after sunrise at 05.00 in Marlborough, was a significant 5.2C above my long-term average.

Wednesday revealed some bright internals at first but cloud built up after around 08.00 from narrow rain bands crossing the area, shown on the rain radar mainly to the south of Marlborough. However, a weak, brief ridge of high pressure will later in the morning bring us a mainly dry day with the possibility of occasional showers.

Tomorrow will see the high pressure sink southwards over France when we will again be in more unstable conditions as the low pressure near Iceland today, sinks south across the UK.

The UK continues to be trapped between the two weather systems. There was a pressure differential at midnight, between the centre of the depression at 990mb and the centre of the anticyclone at 1030mb, thus the wind will continue to be brisk as the air rushes from high pressure to low pressure.

The rise in temperature on Monday was limited by the cloudy conditions that built up around midday with a maximum of 17.6C at 12.37 being just 0.3C above average. The peak UV value of 7.3, the highest since 11th August 2024, took it well into the ‘Very High’ category, but only for a brief period before the clouds thickened and rain showers arrived again, the first at 10.30 then 14.30 and a more consisted fall at 17.00, which in total amounted to 5.8mm making it the wettest day since 28th February. That fall then took the monthly total to 14.6mm compared to my 41-year average of 60.4mm. The past night was very mild that saw the thermometer not drop below 11.7C at 05.2, thanks again to the overnight cloud cover under the hang back of cloud from the weather front.

Tuesday arrived with continuing cloud cover from the unsettled weather as we are still under the influence of the depression to the north of the UK. The rain radar at 08.00 showed heavy rain moving in from the west, already having reached Devon, and making its way to southern England mid-morning, with hopefully for gardeners, a substantial fall. Currently the rain radar indicates that the weather front is fragmented so not sure how consistent the rainfall will be as it crosses from the West Country.

The depression, with its centre just north of Scotland, had a centre pressure of 976mb at midnight, compared to the anticyclone in the eastern Atlantic, reaching across into France, with a centre pressure of 1031mb. This considerable pressure gradient is producing the string winds, that will strengthen in the gusts ahead of the rain arriving mid-morning. The airstream is circulating anticlockwise around the depression and clockwise around the high pressure, as they do, hence the wind from a southwesterly or west-southwest direction today. The barometric pressure at 08.00 read 1012.9mb. There are indications from the rain radar that this approaching rain band will bring a more consistent and heavier fall of precipitation lasting for several hours.

It will all change on Wednesday as the low pressure gives way to a temporary ridge of high pressure that will bring us a much warmer and drier day.

Bowood Gardens, near Calne in Wiltshire, has a large area of varied rhododendrons that are spectacular at this time of the year.

The significant feature on Sunday, weather wise, was the ‘Very High’ UV level with a value of 6.7, the highest since 15th August last year. The very high level occurred in the bursts of strong sunshine, not continuous, until just after 14.00. The maximum of 18.9C was logged at 15.19 being 1.6C above average. The past night was little cooler, although still above average (+2.4C), with a minimum of 9.4C at 05.35 just after sunrise in Marlborough at 05.02. The other significant feature was the strength of the wind with a maximum gust of 24mph, logged at 10.02, the strongest this month.

There was another splash of rain that triggered the automatic rain gauge at 02.39 early this morning amounting to just 0.7mm, another splash that evaporated very quickly after sunrise.

Monday revealed broken cloud and bursts of sunshine that had lifted the thermometer to 12.2C by 08.00. The depression to the north of the UK will continue to feed a predominantly southwesterly unsettled airstream over the UK that as the temperatures rises, will likely trigger some shower activity, but no consistent heavy rain likely.

We are all aware of the very dry months of Spring 2025. Set against my 41-year average, March gave us just 9%, April 20% and May to date is just 15%. This has resulted in a deficit of 154.7mm compared to the average over the three months with just six days left in the season. Although shower activity is forecast in the unsettled weather for the reminder of the month at the moment the only possibility of any substantial rain is likely to be later on Tuesday, but quantities are uncertain. Whilst the rain has been minimal, there has been an equivalent loss of rainfall totalling 223.5mm through evaporation from plant life and the ground due to the many hours of strong sunshine and brisk winds.

Bowood Homes and Gardens: The images this week were taken at Bowood near Calne in Wiltshire, which is a Grade 1 listed Georgian house set in extensive grounds designed by Lancelet “Capability” Brown.

The predominantly cloudy day on Saturday limited the rise in temperature from any sunshine but the much warmer breeze from the west did allow the thermometer to rise to a maximum of 18.5C at 13.29 before cloud thickened, being 1.2C above my long-term average. The past night was mild, thanks to the passage of two weather fronts and their associated cloud that meant the thermometer did not drop below 12.3C, logged at 03.58, being a significant 5.3C above average. The cold then warm weather fronts did not produce much precipitation, a miserable 1.3mm, disappointing for gardeners.

The rainfall total for May now stands at just 8.1mm against the 41-year average of 60.4mm. Although the forecast is for unsettled weather this coming week there is not much optimism for any substantial rainfall at the moment, light rain on Monday and Tuesday is likely.

Sunday after dawn revealed total cloud cover from the hang-back of cloud associated with the weather fronts. However, on the strike of 8 o’clock, the sun broke through and as the cloud thins thi morning, we should have a mainly sunny and warm day.

The low point of the barometric pressure was reached in the early hours with a minimum pressure of 1006.8mb, logged at 05.45, being the lowest pressure all month. There is now a battle between the depression just to the north of Scotland and an anticyclone to the southwest with the winds being hustled from the west between the two due to the considerable pressure gradient, the wind strength will increase this afternoon. The pressure has already begun to rise as the anticyclone begins to assert itself with the battle continuing tomorrow.

The images for the next week or so were taken at the extensive gardens of Bowood near Calne, with the rhododendrons in full bloom.

Friday gave us the last of the very warm and sunny days that saw the thermometer rise to a peak of 20.8C late in the afternoon at 17.34, which was 3.5C above average. It was the second day that the UV level rose to a peak of ‘Very High’ as occurred on Thursday, but we are not far off the longest day so under strong sunshine this UV level is to be expected. A weather front crossed the area overnight that under the thick cloud cover produced a mild night, in fact the warmest night this month, with a minimum of 12.4C logged at 03.23 being 5.4C above my long-term average.

Once again the main rain area avoided Marlborough during the early hours with just 0.4mm that triggered the automatic rain gauge at 02.17.

Thanks to the back end of the weather front, Saturday began with thick cloud cover, however, the significant feature is that the wind is coming from the west after a southwesterly direction later on Friday. This is a direction not seen for over a month after the persistent northeasterlies that dominated most of May. The temperature at 08.00 was 15.2C making it the warmest start to a day this month at that time.

The next few days will be dominated by unsettled weather as we come under the control of low pressure systems arriving from the Atlantic. Currently, the centre of the depression is between Ireland and Iceland, hence the wind direction from a westerly quadrant today as the air moves around it in an anticlockwise direction. The barometric pressure has fallen to its lowest since the 12th having dropped 8mb since yesterday with a reading of 1012.9mb at 08.00. Two weather fronts are forecast to pass over the UK in the next twenty-four hours so sunshine and possibly light showers overnight.