Author: Eric Gilbert

After the record October low of -4.3C the change in direction of the air mass, now from a southerly direction, saw the thermometer rise to 12.2C, the warmest day for a week but still 2.5C below average.

Another 3.6 hours of sunshine.

Thursday arrived with fog, initially at dawn with visibility down to 150m, but by 08.00 was varying from 500m to 1,600m with an ambient temperature of 6.4C.

October Review
October brought us another month of contrasts with some daytime temperatures more likely to occur in August whilst at the end of the month we briefly endured a severe frost that was a record and more likely to be seen in the months of January or February.

The mean temperature for the month was 0.6C below the 34-year average, principally due to cool nights. The daytime mean was 0.5C above average whereas the night mean was 1.6C below average.

The second week saw two days that reached maxima in the 20’s with 22.4C and 21.3C on the 10th and 13th respectively. In contrast the during the early hours of the 31st the thermometer fell steadily to a minimum of -4.3C, this was a record for this station set up in 1984 and equals the same minimum that occurred on 30th October 1992.

A record for the coldest October day since the station began in 1984 was set on the 27th when the thermometer resolutely refused to rise above 5.2C due to strong northerly winds. The October average maximum is 14.7C.

Another example of our variable weather can be seen in that the mean for October 2018 was 9.87C, but in 1992 we experienced a very cool month with a mean of just 6.95C whereas a balmy October occurred in 2001 when the recorded mean was 12.77C.

Turning to rainfall, we have experienced the fourth consecutive below average October rainfall. The total for the month was just 44.6mm, which was 53% of the 34 year average or 40.2mm below. The wet October of 2004 produced 159.3mm whereas the very dry October in 2017 gave us only 31.3mm when the average stands at 84.8mm.

There were two very wet days on the 14th and 15th with 12.7mm and 14.8mm respectively. However, we enjoyed 22 dry days when the average is 14 dry days.

My sunshine recorder was only installed in 2014. October 2018 was a very sunny month as we enjoyed 130 hours of strong sunshine (<100watts /sq.m.) that contrasts with the average for the previous four years of 73 hours. Still on the theme of contrasting weather, the diurnal data for October shows just how much we as individuals have to adjust on a daily basis. The minimum temperature variation between day and night on the 6th was just 2C whereas a range of 17.3C occurred on the 31st as the severe frost rapidly cleared during the morning as a gentle southerly air mass arrived. This quotation from Percy Shelley sums another colourful season: “There is a harmony in autumn, and a luster in its sky, which through the summer is not heard or seen, as if it could not be, as if it had not been!”

Although we had another 2.8 hours of sunshine on Tuesday there was much more cloud and the thermometer struggled to reach a maximum of 7.7C, which was 7.1C below the 34-year October average. However, it was another dry day, the 22nd this month.

The clear skies overnight meant a severe ground and air frost was recorded. The minimum of -4.3C, at 03.32 this morning, was a record for this station that was set up in 1984 and equals the record minimum on 29th October 1997.

Wednesday initially arrived with clear skies but a bank of cloud drifted across obscuring the sun. By 08.00 there were breaks in the cloud allowing glimpses of sunshine and the thermometer had recovered to -1.1C.

Update at 18.20 on Wednesday: southerly air flow lifts temperature to a maximum of 12.2C early in the day after sharp frost at 10.59. However, this was still 2.5C below average.

The barometric pressure fell steadily all day on Monday as the deep depression over the continent moved northwards skirting our east coast today. This was Storm Adrian named by the French Meteorological Office.

Monday gave us 6.7 hours of sunshine although that did nothing for the temperature as it struggled to reach 7.7C, a significant 7C below average, due to the brisk northeasterly wind.

Although the thermometer fell away overnight to a minimum of 0.2C at 02.16, the advancing cloud from the nearby storm began to lift the temperature so that by 08.00 it reached 2.2C although evidence of the hard ground frost could still be seen on the ground.

Just before midnight the wind began to back from the Northeast into the North and this morning has backed further now coming from the Northwest as the nearby storm progressed northwards across the near continent.

Tuesday arrived with the lowest barometric pressure for month with a reading of 996.3mb at 06.17. Thick cloud produced a few spots of rain just after dawn but subsequently the sky began to lighten as the depression eased north eastwards.

Sunday saw the thermometer ease upwards to a maximum of 9.0C but this was still 5.7C below average although up almost 4C on the low Saturday peak.

Another 4.35 hours of sunshine was logged and mid-morning there were a few spots of rain but not sufficient to measure hence the term ‘trace’ in the records.

With clear skies overnight the thermometer fell steadily to reach a low of -0.3C making it the coldest night in October, being 7.7C below average.

Monday arrived with clear skies and the sun shining brightly as it rose above the horizon. However, a bank of fog to the north slowly drifted southwards arriving over Marlborough just before 07.30 that by 08.00 limited visibility to 500m. Within 15 minutes this had cleared although banks of cloud then obscured the sun.

Update on Monday at 17.35: thermometer again refuses to rise above the average, the third successive day for October with a maximum of 7.7C being 7C below.
Barometric pressure falling steadily all day as deep depression edges northwards from the continent with drop of 10mb in 12 hours.

Although we had 3.4 hours of sunshine on Saturday morning, cloud cover increased after midday, the thermometer resolutely refused to rise above 5.2C. This was 5C down on the Friday peak and 9.5C below the 34-year average. In fact it was the coldest October day since 29th October 2008 when the maximum was 5.0C.

The wind, then coming from the north and gusting to 24mph produced a wind chill so that it felt more like 2C.

There were a few brief showers in the afternoon and evening that amounted to 4.0mm.

Overnight the thermometer fell back to 1.9C just after 2am with windchill making it feel more like -1C. Subsequently the cloud thickened as the wind veered into the northeast so that by 08.00 the temperature rose to 4.6C.

Sunday dawned with thick cloud and drizzle and the northeasterly having abated a little.

Update at 15.20 on Sunday: temperature eased upwards with maximum of 9.0C, which was still 4.7C below average but up 4C on Saturday peak.