Category: Commentary

Sunday proved to be the second warmest day this month with the thermometer peaking at 22.5C, which was 3.6C above the 38-year average. There were many hours of strong sunshine during which the UV level rose to 5.0, just in the ‘High’ category, and the highest this month.

The east night was mild with the minimum logged at 00.05 with a low of 13.9C being 4.6C above he average.

Dawn on Monday revealed misty conditions with radiation fog forming for a brief period in the River Og Valley and River Kennet Valley. This had readily dispersed by 07.45. There were brief bright intervals after sunrise but by 08.15 the cloud had begun to thicken. The barometric pressure has begin to slip away with a reading at 08.00 of 1012.8mb, a drop of 7mb since Sunday morning.

The variable sunshine on Saturday boosted the temperature to 20.8C being 1.9C above average even though the very light breeze was from the north. The peak gust of 11mph was the lowest maximum gust since 26th July.

As the temperature dropped steadily overnight to a low of 8.9C, radiation fog formed. The minimum of 8.7C was logged at 05.41 being 0.6C below the average and the coolest night since 6th August (5.8C).

Af first light it was obvious that the fog was thick with visibility limited to less than 200m. However, the sun began to get to work shortly after dawn and by 07.45 there were visible signs of it beginning to thin. By 08.00 the temperature had recovered to 11.7C. The barometric pressure has eased a little higher again with a reading of 1019.5mb at 08.00 so a fine, dry and warm day should be ahead.

After almost a week under the low pressure system to the west it finally moved off to the east with a consequent change in our weather. The wind backed into the northwest, not seen for a month, and a dry day. The wind was lighter and with strong sunshine in the afternoon the thermometer rose to 20.4C, which was 1.5C above the average.

It was a mild night with the temperature no lower than 12.0C being 2.7C above the average due to cloud cover. At 04.06 a small shower passed over producing 0.6mm of rain. Most of the evidence of this had disappeared shortly after dawn as broken sunshine greeted the new day.

Due to the departure of the depression the barometric pressure has been rising with a reading of 1015.4mb at 08.00, up 10mb in the past twenty-four hours.

Another 7.2mm of precipitation fell on Thursday afternoon during a thunderstorm at 15.30. That brought the monthly total to 35.1mm when the 38-year average is 66.9mm. The September total is now greater than was the combined total for July and August. The five continuous days with rainfall we have just experienced has not occurred since 14th-18th May.

Due to the overcast conditions and thick cloud associated with the storm the maximum of 18.7C was just below the average (-0.2C) making it the first below average maximum since 25th August. The depression brought all the cloud and rainfall as it moved very slowly across the UK that meant the wind veered into the southwest for much of the day.

The overcast conditions overnight meant another mild night when the thermometer did not fall below 14.1C, which was 4.8C above the average.

The diurnal temperature range, the difference between maximum and minimum, was just over 4C compared with a range of 11C earlier in the month.

Friday dawned with the overcast conditions still prevailing but at 08.24, as I write, the sun broke through, if briefly.

The low pressure has begun to move away to the east with the barometric pressure starting to rise with a reading at 08.00 of 1005.5mb, up over 2mb from the low yesterday. As the centre of the low moves slowly away the wind is forecast to veer into the north-northwest or north west today.

Both the maximum of 20.4C and the minimum of 12.8C were above the 38-year average with +1.5C and +3.5C respectively. However, the past five days have seen a gradual decline in daytime temperatures as the ridge of high pressure receded and taken over by the slow moving depression to the southwest. The maxima for the past five days have been 22.6C, 22.2C, 21.9C, 20.7C and 20.4C. respectively. A sign of late summer and approaching Autumn, perhaps?

There was a shower at 20.20 also two very brief showers early this morning amounting to 2.4C that brought the monthly total to 27.9mm when the 38-year average is 66.9mm.

Thursday produced a mainly cloudy start to the day with occasional glimpses of brightness but no sunshine.

The slow moving depression, that has lingered in the western approaches for several days, appears to making a move and forecast to move across the UK. Today it is closer and given us the lowest barometric pressure this month and since 15th August of 1003.5mb at 08.00.