Author: Eric Gilbert

After the coldest night since January, Friday during daylight hours, brought us the coldest day since 5th March as after the hard frost the thermometer struggled to reach 5.4C at 13.46. However, we were not encased in fog that was close to the north, and occasionally crept over the Marlborough Downs towards Marlborough but not reached, as we enjoyed 3.4 hours of sunshine in the morning that faded away after 13.00. The temperature dipped to 3.3C late afternoon at 16.00 before recovering overnight to reach 7.1C at 08.00 on Saturday. The wind on Friday was from the northeast but a subtle change late in the afternoon on Friday saw it veer into the east allowing slightly warmer and moist air to arrive.

A fragmented band of rain crossed the area during the early hours of Saturday producing 0.7mm of rain that triggered the rain gauge at 04.45.

Saturday dawned with fog that limited visibility at first to 200m. I suspect that the fog is due more to a very low cloud base than the moist air travelling over the cold ground condensing in the almost still air.

The ridge of high pressure brought a fine day on Thursday, after a cloudy start, but the air mass, very calm with a maximum gust of just 7mph, was from the north-northeast. As a result of the cooler air the thermometer struggled to reach 8.4C at 14.06 during the 3 hours of sunshine, which was 1.6C below average. It was the coldest day since 28th April.

As the afternoon moved into the evening the thermometer slowly fell away and reached -0.1C at 19.32 when an air frost began to develop. The minimum reached at 08.05 on Friday morning was -3.7C. This made it the coldest night in 2020 and equalled the minimum on 21st January 2020 being 7.4C below the 36-year average.

Fog formed in the early hours, after a misty evening, that limited visibility to 400m at dawn on Friday but slowly evaporated so that by 08.40 visibility had increased to 1200m as the sun began to rise bringing weak sunshine. The high pressure is still dominant so another fine day is in prospect.

Although no sunshine occurred on Wednesday the thermometer again rose above average (+1.4C) with a maximum of 11.4C. The wind direction was initially from the south but slowly veered from the west and then northwest.

Rain during the morning ceased just before midday and totalled 3.1mm that brought the monthly rainfall to 70.2mm when the average is 92.3mm.

During the late afternoon and early evening the thermometer slowly fell away to reach 0.0C at 22.24 then -0.1C at 22.29. The recognised classification of an air frost is when the temperature reaches -0.1C therefore there was a very brief period when an air first occurred last night. However, by 23.00 the thermometer had risen to +0.1C and continued to rise until 01.15 early on Thursday reaching 1.6C before falling again.

The minimum of -0.8C was reached just after dawn on Thursday with the cloud having eased away to the east allowing a little brightness at 08.00. A temporary ridge of high pressure, and the air now coming from the north-northeast, will produce a cooler day but dry and bright.

Tuesday morning saw the cloud break allowing broken sunshine in the morning (two hours) that raised the temperature to 10.00C. The afternoon and evening saw the temperature fall away to 8.9C at 18.52 before rising again to a peak of 10.9C at 08.00 on Wednesday.

A cold weather front began to approach the area during the early hours of Wednesday with increasing cloud that allowed the thermometer to rise in the early hours. Rain began to fall at 07.25 and a heavier burst at 08.35.

By 09.00 the temperature had risen further reaching 11.4C, which is very mild for late November and 1.4C above average. The breeze for much of Tuesday came on a southerly air flow that continued in the early hours of Wednesday. However, as the cold front eases away to the east the wind is forecast to make a 180* turn to come from the north later in the day.

The air mass on Monday, coming from the south-southwest, brought another mild day with the thermometer rising to 10.4C after a chilly start. This peak was 0.4C above average. It is interesting to note that only one day this month has produced a below average daytime peak, which was the third when the maximum was 0.1C below average. The mean temperature for November is approximately 2C above average.

The temperature rose a degree during the late evening but after midnight fell away to a minimum of 9.0C being 5.3C above average. There was a light shower just after 03.00 that amounted to 0.7mm.

Tuesday saw cloud after dawn with the prospect of bright intervals later. Monday was another day with very light winds with a peak gust of 9mph but the wind is freshening this morning due to the barometric pressure falling away with a drop of 10mb over twenty-four hours as the anticyclone eases away and another depression advances from the Atlantic.