Category: Commentary

The breeze from the northeast on Friday limited the rise in temperature again with a maximum of 9.6C at 13.13, however it was 1.3C above the long-term average. The highest value of UV light was recorded with a reading of 2.1, being at the top end of ‘Low’. The equivalent loss of rainfall of 1.35mm, due to evaporation from ground sources and plant life, was the highest since 5th October. This was a result of the many hours of warm sunshine and lower air humidity on a light northeasterly breeze, following the considerable rainfall on previous days.

Saturday revealed that the barometric pressure had risen again with a reading of 1034.2mb as the anticyclone intensified. The downside was a hard air frost with the minimum of -4.1C recorded at 07.00 before the sun got to work.

February 2025 Review

The month began with three mild days that produced above average maxima with the wind from the south, peaking at 10.7C on the 3rd, which was 2.4C above the average.

It all changed when a large area of high pressure developed over the country extending east across to the far Continent. The barometric pressure on the 6th was logged at 1044.7mb, an unusually high pressure. That was the highest pressure since 5th February 2023. The anticyclonic dome brought cold, moist air on a persistent northeasterly that depressed temperatures by day, the maximum of just 3.1C on the 10th was the coldest day 10th January. These were depressing days.

Nighttime minima were mostly above average due to the continuous thick cloud that acted as a duvet restricting the loss of any warmth into the atmosphere.

On the 9th a very large area of low pressure in the eastern Atlantic pushed a very wide rain band across the country, the most significant precipitation for a week, with a fall of 16.2mm recorded.

The diurnal range of temperature, the difference between night and day extremes, was unusually small on the 10th with 3.1C by day dropping to just 2.3C overnight, thus a difference of just 0.8C.

The high pressure persisted throughout the second week with very cool, moist air on a modest northeasterly breeze. There was no sunshine to produce any warmth by day, just gloomy weather, although the wind was light with minimal wind chill.

The first indication of a change from the cold, gloomy days was sunshine on the 17th that saw the UV light sufficient to trigger the UV sensor continuously between 10.00 and 16.00 with the greatest strength since 31st October, with a reading of 1.3, even so it was still in the ‘Low’ category.

After a ten day battle the high pressure gave way to the depression on the 19th that brought a significant change in our weather. The cold, gloomy days with calm conditions gave way to more unsettled conditions with welcome higher temperatures but periods of rain. The barometric pressure dropped to its lowest all month with a low of 1004.4mb on the 21st.

The stream of warm air from around the Azores region saw maximum temperatures rise again to double digit maxima with 13.4C logged on the 21st being 4.1C above my long-term average.

The wettest day of the month occurred on the 23rd when several hours of continuous rain, heavy at times, produced a daily total of 18.0mm. In the first of two short but sharp showers on the 24th small hail (classified as less than 5mm in diameter) were observed that in the space of ten minutes saw the temperature drop over 3C.

An anticyclone developed in the eastern Atlantic throwing a ridge across the country on the 27th producing a significant change in our local weather with fine dry days although nighttime air frosts occurred under clear skies as it’s centre settled over the country, just to the north of Marlborough.
The high pressure built on the 28th that saw the highest UV all month with a reading of 2.1, which was at the top end of ‘Low’, also the highest since 18th October 2024. Because of the many hours of sunshine and the light breeze that was less humid, the equivalent loss of rainfall due to evaporation from ground sources and plant life was 1.35mm.

The total rainfall for the month was 76.2mm being 112% of the 40-year average or plus 8.2mm. There were three days when fog was observed in the morning and one day when small hail was observed.

Once again, although, we had many hours of sunshine on Thursday we were still under the flow of cool air brought on a northwesterly and later a northerly airstream from the north Atlantic, not Arctic, so it moderated the rise in temperature. The maximum of 9.8C was logged at 14.39 being 1.4C above my long-term average. The clear skies saw the thermometer fall slowly late afternoon and early evening registering freezing point (-0.1C) at 22.29 where it hovered until after 01.30 when it fell further with a low of -2.7C at 07.40 early Friday, which was 4.5C below the average.

There were two significant meteorological events on Thursday registered on my station. The UV light was the strongest since 25th October with a value of 1.8 at its peak being at the top end of ‘Low’. The equivalent loss of rainfall through evaporation from ground sources and plant life totalled 1.32mm being the highest since 5th October as the ground had been very wet following the recent substantial falls of precipitation.

Friday revealed a sunny start to the day, even if the sun’s strength was weak initially. There were misty conditions at first with fog observed rolling in from the north after 07.40 but then receded and dispersed by 08.15. The thermometer climbed back above freezing at 08.18. The air stream has veered into the northeast today although the conditions last night and this morning are calm with the anemometer stationary.

The anticyclone has built considerably over the past twenty-four hours and is centred just to the north of Marlborough with the pressure reading at 08.00 of 1030.2mb, a rise of 10mb since Thursday at that time. This is going to give us a few fine, dry and sunny days although air frosts are likely to occur during the next two nights.

The synoptic charts indicate that this high pressure system will be dominate our weather for the next few days with much sunshine although not high temperatures as the air stream until Monday will come predominantly from a northerly quadrant, when it is then forecast to back into a westerly quadrant, which will see the daily temperatures begin to rise with the end of night frosts.

After a very wet morning the intense rain from the weather front eventually ceased just after 11.30 adding another 10.8mm to the monthly total that now stands at 76.2mm being 8.2mm above the long-term average. Due to the hang back of cloud from the weather front that dominated the afternoon the thermometer only rose to a maximum of 9.3C, but this was 1.0C abject the average. Overnight the temperature remained quiet stable around 4.5C but as the last of the cloud cleared it dropped after 05.15 to reach a minimum of 3.2C at 07.20 early Thursday.

Thursday saw the last of the cloud disappearing eastwards over the horizon with the sun making an appearance just after 07.45. The humidity at 08.00 was 84%, the lowest since the 17th, as the drier air from the anticyclone arrives.

The large area of high pressure in the eastern Atlantic is today throwing a ridge of high pressure over the UK having risen 6.4mb since yesterday. With the barometric pressure continuing to rise as the day progresses, thus squashing out any showers, although cloud is likely to build after midday as the temperature rises due to the moist air condensing as it rises into the cooler high air.

This change in the position of the anticyclone and its associated ridge has seen the wind veer from the west yesterday into northwest overnight and likely into the north-northwest day this being a cooler direction it will moderate any temperature rise although much sunshine is expected. It is not a cold air stream, although from the northwest, as it originates in the northern sector of the Atlantic, not from the Arctic region, as the air travels clockwise around the high pressure dipping down across the UK. The ridge is acting as a blocking high keeping the next depression at bay, and likely to for the next few days.

Tuesday was a splendid day with much sunshine that although the wind came from the northwest, a cooler direction, saw the thermometer climb to a maximum of 10.6C at 14.32 being 2.3C above the long-term average. The UV strength rose to a peak of 1.5 between 12.00 and 14.00, the highest level since 31st October, so evidence that the sun is getter stronger. Therefore, it was not surprising that the level of daily evaporation from plant life and the ground was equivalent to a loss of 1.02mm of rainfall.

The warmth slowly dissipated during the evening, to level out just before midnight with a temperature of 2.9C, and reached a minimum of 2.7C at 04.10, being 0.9C above average. The temperature had recovered to 5.4C by 08.00 as the cloud had thickened ahead of the rain bands.

Two weather fronts have combined this morning to bring us a minor disturbance between the sunny days, that will moved eastwards, indicating a drier afternoon. The first rain drops were observed this morning at 06.35 with steady rain following that by 08.00 totalled 3.5mm with a couple of hours of rain still to come.

The forecast synoptic charts show an area of high pressure moving closer to the UK tomorrow, with a ridge developing across the country, which is likely to bring us a few dry and sunny days. This will form a blocking high fending off the forecast deep low pressure system developing to the northwest.

Monday brought us a very sunny morning that was spoilt by the two short but heavy showers around midday. These were from the two rain bands that the rain radar indicated were over mid Wales at 08.00 and heading our way. The first shower was intense at 12.30 and just after it started small hail (less than 5mm in diameter) was observed and the temperature dropped almost 3C within ten minutes from a peak of 12.3C. Before the rain arrived this was the warmest part of the day with the maximum of 12.3C at 12.29 being 3.9C above average with the thermometer around 11C for most of the afternoon. It was also at this time the peak solar radiation was logged at 673 W/m2 being the highest all month and in fact the highest since 7th October, so perhaps Spring is on its way.

The temperature overnight stabilised around 7C until dropping after 03.00 to reach a minimum of 4.5C at 06.58 early Tuesday, as the cloud began to thin, which was 2.7C above average.

Tuesday revealed the thick clouds from the back edge of the recent weather front over the eastern horizon and easing eastwards. The barometric pressure has also risen a few millibars as a short-loved ridge, which will calm things down today bringing minimal rain and calmer conditions. The reading at 08.00 was 1012.6mb. The wind has veered a few degrees, from the southwest yesterday to west-northwest for much of the day, a slightly cooler air flow for much of the day, that will limit the rise in temperature, but mostly dependent on the amount of sunshine we receive.

The forecast pressure charts show an expected rise in pressure over the next few days, spoilt by a minor disturbance around midday tomorrow, that should bring us much more sunshine up to the weekend and calmer conditions. This will be the result of a high pressure system in the Atlantic, developing off the coast of Iberia, and slowly edging our way.