Category: Commentary

Although in the sunshine on Thursday it felt warm out of the breeze the thermometer only reached 21.9C, it was still below average at -0.9C. The minimum of 12.3C was above average thanks to the chide cover again, which was +0.4C.

Friday revealed another cloudy, dull start to the day. A frontal system has been slowly moving southwestwards overnight, after the wind veered into the northeast, a cool direction, around 22.00 on Thursday night. The cool air is being brought from Scandinavia today, so not a warm day ahead. The rain band is fragmented but by 08.00 had reached the Swindon area so a cloudy, cool, likely damp morning ahead. The wind is forecast to back into the north later today.

Although there was warm sunshine on Wednesday it didn’t push the thermometer above my 40-year average with a peak of 21.6C at 14.20 being 1.2C below the average. However, it was a dry day and in the sunshine the UV level rose into the Very High category. The past night was a little cooler than the previous two nights with a minimum of 11.1C, which was 0.8C below the average.

Thursday dawned with welcome strong sunshine that lifted the temperature to 15.8C by 08.00.

The old depression is very slowly easing away over Scandinavia with the anticyclone in the Atlantic showing a modest rise in the barometric pressure over the UK with a reading of 1018.1mb at 08.00, the highest pressure since the 2nd. This should give us a better day, predominantly dry with variable sunshine. The breeze will continue from the west.

Over much of this month the Jet Stream has been to the south of the UK acting as a conveyor belt for the depressions coming in from the Atlantic leaving us on the cooler north side. The forecast does not show any significant change in its position for next week.

A high of just 18.4C, high humidity and the UV level in the ‘Low’ category on Tuesday was more like an autumn day than summer. The peak was 4.4C below my 40-year average with the minimum of 14.4C at 04.11 early Wednesday 2.5C above the average. The mild night was due again to thick, low cloud cover minimising any loss of warmth into the atmosphere. The drift of south-southwest breeze also kept the temperature higher. Another night with a minimal diurnal range, this time of just 4C.

The light rain that began just before 13.00 amounted to 0.7mm.

The start to Wednesday revealed another dull morning, however, the cloud is higher and not as thick as on Tuesday. The depression has eased away to the northeast, now centred over northeast Scotland, so beginning to lose its influence.

An anticyclone in mid-atlantic is showing signs of producing a ridge of high pressure over the UK as the depression moves away. As a result, Wednesday is likely to be drier with the wind veering into the west but strengthening.

Although Monday morning was predominantly dry outbreaks of sporadic rain started after 13.00, although the main rain band arrived just after 18.00 and lasted throughout the night producing another 13.6mm of rainfall. That additional precipitation took the monthly rainfall total to 49.7mm, exactly 10mm below my 40-year average.

The cloudy conditions, combined with the wind that became brisk and from the southeast, a cooler direction and not seen for two months, meant a very cool day. The thermometer struggled to reach a maximum of just 16.7C late in the afternoon at 16.29 being a significant 6.1C below my 40-year average. The thick cloud and rain overnight minimised any loss of warmth into the atmosphere, providing a duvet, that saw the thermometer drop just 3.5C to a low of 13.2C at 00.02. A diurnal range of just 3.5C is unusual for the summer months. This low was 1.3C above average and made it the warmest night since 22nd June.

Tuesday struggled into the new day under low, thick cloud with light rain and drizzle still falling. The backend of the weather front is still slowly receding northeastwards. The centre of the depression is just off the west coast o South Wales and will continue to feed us damp, dull conditions for much of the day although the precipitation will be much lighter. The mainly south or south-southwest air stream is coming further south than recently. from near Iberia, so a little warmer than of late. Being positive, I won’t need to water my hanging baskets for a second night, although they are looking g bedraggled!

At least there was little rain over the last twenty-four hours, unlike the previous day, just 0.6mm, but the temperatures were once again depressed. The high of 19.0C was 3.8C below my forty-year average but in the early hours of Monday the thermometer dropped very low for July, of 6.2C at 05.46, being a significant 5.7C below average.

The low temperature overnight, combined with much moisture over the last two days, meant that radiation fog formed in the River Og and River Kennet valleys. After sunrise the visibility was limited to just 200m, but at 06.30 the sun began to break through and the fog disappeared within minutes over the Og, however, the thicker fog over the River Kennet swirled around and took a little longer to clear. The strong sunshine then lifted the temperature to 12.8C at 08.00.

As a depression forms over the Bay of Biscay, the wind will back from southwest yesterday to southeast today, a direction not seen for almost two months. The high pressure far to the west is still having a marginal influence in that the barometric pressure has risen 15mb over the most two days with a reading of 1015.0mb today at 08.00, but not strong enough to kill off the numerous, heavy showers likely today or more persistent rain this evening.