Monthly Weather Review - Pitsford Hall

Headline: A month of two halves: cyclonic at the start with frequent showers and some torrential downpours of rain, then a prolonged spell of dry and settled weather as high pressure remained resident across the UK.

September began with an area of low pressure forming across the British Isles. The weather for day one would very much characterize the rest of the month which was to become distinctly autumnal with no sign of an Indian summer to compensate with the poor weather in August. Despite the bright start and the mainly west or south-westerly breeze the day was cool. Cloud developed later bringing showers. These became heavy and thundery at times on the 2nd with even reports of a tornado in Northampton later in the day. Conditions remained cyclonic over the next few days with continued heavy showers and some torrential downpours on rain particularly on the 5th and 6th which saw 20.4mm and 32.7mm respectively fall at Pitsford. Floodwatches were issued on the River Tove on the 5th and on the 6th the emergency services were busy diverting floodwater from overflowing drains in many parts of Northampton. The low filled and moved steadily eastwards over the next few days. There were further showers, although there was a noticeable trend towards warmer temperatures with some spells of sunshine.

By the 10th a new low had started to work across the far north of Scotland. Attendant fronts brought renewed rain across the south and Northamptonshire included over the next few days. The rain on the 11th was mainly light, but the following day saw heavier and more prolonged spells of rain. Temperatures, having recovered to a high of 20.2C on the 10th at Pitsford, fell to below average over the following days as the wind swung round from the north-west. Once a second deep low had swept past the north-west of Scotland on the 11th, pressure remained fairly slack across the region. Weak frontal systems continued to wander across the UK bringing further showers and outbreaks of rain to the county. In between the showers there were decent spells of sunshine allowing temperatures to recover. Highs reached 19.4C at Pitsford on the 13th and remained respectable on the 14th and 15th.

High pressure which had been resident over Scandinavia since the 8th expanded south-westwards towards the UK on the 15th to link up with the Azores high. As these systems merged, some old weather fronts became trapped beneath the growing anticyclone. These contributed to a fair amount of cloud. However, the main impact came from the easterly breeze which allowed some fairly extensive low cloud over the low countries and North Sea to drift across and envelope the eastern side of the UK including Northamptonshire. The 16th and 17th were particularly dull.

By the 18th the UK was clear of frontal systems save for the far north-west and as the Scandinavian high extended its influence the cloud blanket was broken by good spells of sunshine. Over the next few days daytime temperatures would climb towards 19.9C on the 20th although overnight temperatures would occasionally reflect the shortening days and clear skies resulting in fairly widespread mist during the early mornings. High pressure over Scandinavia had retreated on the 21st, although the UK continued to enjoy the dry weather associated with the dominance of a new high developing west of Ireland. A cold front on its leading edge introduced some light showers across the county on the 22nd and 23rd, but otherwise it would remain dry pretty much for the remainder of the month as the high showed a characteristically slow movement across the UK. Initially, the high secured some good spells of sunshine but it became increasingly cloudy later on low cloud developed overnight. As the centre of this high drifted over the North Sea on the 26th, the wind across the county veered to a more southerly direction. Temperatures correspondingly rose and in the sunshine the county enjoyed a pleasantly warm autumn day.

As the month came to a close an active low pressure system swept in across the UK from the north-west. It became noticeably quite windy, particularly on the 30th as gusts reached 35mph, and there were showers and occasional outbreaks of rain. What was a brief hint of an Indian summer soon disappeared to a characteristically autumnal last two days where temperatures struggled to reach the seasonal norm.

Air Temperatures    
The Highest Maximum:    20.2 C on 10th
The Lowest Maximum:    14.9 C on 16th
The Highest Minimum:    13.3 C on 11th
The Lowest Minimum:    5.2 C on 27th
The Mean Maximum:    17.5 C  
The Mean Minimum:    9.9 C  
The Overall Mean:    13.7 C  
Difference from the Monthly Mean:  0.0 C  
    
Black Bulb    
Maximum (at 0900):    21.3 C on 2nd
Mean (at 0900):    16.6 C  
    
Relative Humidity:    
Highest Relative Humidity (at 0900):  100.0 % on 27th
Lowest Relative Humidity (at 0900):  67.1 % on 15th
Mean Relative Humidity (at 0900):  87.9 %  
    
Dew Point:    
The Highest Dew Point (0900):   13.6 C on 10th
The Lowest Dew Point (at 0900):  8.7 C on 15th
The Mean Dew Point (at 0900):   11.3 C  
    
Rainfall:    
Total:      94.4 mm  
Difference from the Monthly Mean:  166.5 %  
Duration:     58.2 hrs  
Highest 24 hour fall (0900 to 0900):  32.7 mm on 6th
Rain Days (>/=0.2mm):    15   
Wet Days (>/=1.0mm):    11   
    
Sunshine:    
Total Duration of Bright Sunshine:  106.9 hrs  
Sunniest day:     8.1 hrs on 20th
No. of days without sunshine:   4   
Difference from the Monthly Mean:  80.7 %  
Cloud cover (mean at 0900):   6.2 oktas (77.5 %)
    
Pressure (reduced to sea level):    
The Highest Pressure:    1038.2 mb on 26th
The Lowest Pressure:    991.8 mb on 6th
Mean Pressure (recorded at 0900):  1017.5 mb  
    
Winds    
Run of wind (mean over 24 hrs):  80.0 miles  
Mean daily wind speed:    4.3 mph  
Run of wind (cumulative):   2398.9 miles  
Highest Maximum Gust:   35 mph on 30th
No. of gusts of 50mph or more:   0   
Highest wind strength (at 0900):  11.5 mph on 4th
Mean wind strength (at 0900):   5.9 mph  
    
Winds from the Following Directions:    

N 2 NE 1 E 6 SE 3 S 6 SW 6 W 2 NW 3 Calm 1
    
Concrete     
Lowest Concrete Minimum:   3.8 C on 27th
Mean Concrete Minimum:   8.5 C  
    
Evaporation    
Piche      56.1 ml  
Pan      33.97 mm      

Days with:    
Thunder: 1   
Hail <5mm: 0   
Hail >/=5mm: 0   
Snow or snow & rain: 0   
Snow lying: 0   
Fog: 1   
Air Frost: 0   
Gales: 0   

All data © Pitsford Hall weather station.

The weather station publishes a full Monthly Weather Report (ISSN 1741-4733) which is distributed to libraries across Northamptonshire. This report comprises a full UK weather diary, reports of extreme weather events across the county, statistics from Pitsford Hall's affiliated stations across the county as well as news from the weather station itself. Individuals may download this report for £2 or take out an annual subscription for the paper-based report for £25. Click here for further details.