Tuesday 22nd September
The warmth built on Monday, after a slow start, that eventually peaked at 23.9C being 4.7C above my long-term average with the sun very strong in the afternoon. The peak barometric pressure of 1033.5mb was the highest since last December that occurred at 11.12 as the centre of the high was almost overhead.
There was very little air movement after a calm night, being under the high pressure. In fact during the night when the anemometer was stationary, gossamer threads had floated in the still air and wrapped themselves around the high anemometer, which I had to remove with an extended pole.
The past night again saw the air become still after 20.00 with no moment overnight. Under those conditions and clear skies the temperature dropped to a minimum of 9.8C that was just above the September average.
Tuesday after first light revealed foggy conditions. The moisture in the atmosphere had condensed in the early hours to form fog that limited visibility to 200m at its most dense point, an hour after sunrise at 06.52 in Marlborough, that took until just before 08.00 to burn away and restore visibility to almost normal. After the fog had cleared there was high, thin cloud that obscured the sun for the first part of the morning.
The latest cloud radar (09.00) indicated that a bank of high, thin cloud had replaced the fog that could result in sunny intervals today, not wall to wall sunshine as yesterday.
The slight relocation of the centre of the anticyclone to the east will produce a light breeze today, but significantly, it has backed into the south, which will mean an even warmer day today.
The high pressure over the next few days will slowly edge eastwards that will result in the air flow from Thursday onwards coming from a more southeasterly direction that will see maximum temperatures drop closer to the seasonal average, but little sign of any rain until possibly next week.
The forecast track of the jet stream indicates that it will make a significant change in direction after the weekend and not loop north over the UK that has allowed the high pressure to arrive from the warmer south. It appears that the track will be more direct across the Atlantic probably heralding a change to more unsettled weather from Tuesday onwards.
The image is of a spider hacking constructed its web under the still, moist conditions overnight.