Monthly Weather Review - Pitsford Hall

Headline: Cool and unsettled at the start, becoming drier and very warm at times later.

July opened with high pressure over the south-eastern corner losing ground to a deepening low west of

Ireland

. The high maintained a dry day on the 1st with some 10.6 hours of recorded sunshine at Pitsford and with daytime temperatures climbing to 25.4C. However, an active cold front was ushered in on the 2nd delivering rain and noticeably cooler temperatures. The county escaped with a largely dry day on the 3rd, a succession of troughs passing close-by to the south. However, on the 4th an intense low pressure system moved up quickly from the south-west introducing outbreaks of rain and a freshening southerly breeze. This low would remain over the UK for the next few days driving a particularly unsettled spell of weather across the county. Some significant amounts of rain were recorded including 8.8mm over 4.5 hours at Pitsford on the 6th. The 7th and 8th were also fairly wet days. On the 8th the low had started to fill and drifted over the North Sea. However, it was quickly followed by another active low producing a very wet day on the 9th (12.6mm) and again on the 11th (14.0mm). The heavy rain caused damage to ripening fruit on some county farms and some particularly torrential downpours on the 11th caused problems on roads owing to reduced visibility.

On the 12th this second low had drifted over the North Sea and a ridge of high pressure from the Azores had started to influence conditions across the UK. Over the next few days temperatures would rise in Northamptonshire towards a high of 25.0C on the 15th. Winds also fell to a mainly light westerly. Although high pressure was influencing the weather across the southern half of the British Isles, the north was affected by the proximity of low pressure over Iceland. A cold front tied into this system swept southwards later on the 15th and on the 16th the county was left in a cool and overcast north-westerly airstream which brought outbreaks of rain overnight. Over the next few days pressure remained fairly slack. The days continued largely overcast and cool for the time of year with some showers.

An area of low pressure passed to the north of Scotland on the 19th. The passage of the low brought little rain to the county, although the wind picked up to a fairly fresh west or north-westerly. On the 20th the Azores high began to build up from the south-west. High pressure remained dominant across the county through to the 25th, although becoming detached from the Azores and drifting very slowly north-eastwards. Winds eased and swung round from the east or south-east later in the period and temperatures recovered rising steadily from the low to high 20s.

High pressure began to lose direct control from the 26th moving to a position over Scandinavia. However, with very warm air still coming in off the near continent the heat did start to trigger some sharp thundery showers. Temperatures continued to rise to a maximum of 28.7C on the 28th.

As the month drew to a close, a complex area of low pressure west of Ireland began to exert more of an influence across the UK. Across Northamptonshire there were frequent showers. Some particularly sharp showers on the 27^th caused some concerns about flooding in parts of Northampton. Whilst cooler than the peak of the heat on the 28th, it remained warm and at times humid in the southerly airflow.

Air Temperatures    
The Highest Maximum:    28.7 C on 28th
The Lowest Maximum:    16.1 C on 17th
The Highest Minimum:    16.4 C on 27th
The Lowest Minimum:    8.0 C on 4th, 5th & 21st
The Mean Maximum:    21.3 C  
The Mean Minimum:    12.0 C  
The Overall Mean:    16.7 C  
Difference from the Monthly Mean:  -0.1 C  
    
Black Bulb    
Maximum (at 0900):    33.2 C on 1st
Mean (at 0900):    22.2 C  
    
Relative Humidity:    
Highest Relative Humidity (at 0900):  95.7 % on 9th
Lowest Relative Humidity (at 0900):  44.8 % on 1st
Mean Relative Humidity (at 0900):  77.6 %  
    
Dew Point:    
The Highest Dew Point (0900):   18.6 C on 27th
The Lowest Dew Point (at 0900):  7.5 C on 1st
The Mean Dew Point (at 0900):   12.8 C  
    
Rainfall:    
Total:      62.6 mm  
Difference from the Monthly Mean:  130.7 %  
Duration:     40.4 hrs  
Highest 24 hour fall (0900 to 0900):  14.0 mm on 11th
Rain Days (>/=0.2mm):    12   
Wet Days (>/=1.0mm):    12   
    
Sunshine:    
Total Duration of Bright Sunshine:  188.4 hrs  
Sunniest day:     13.6 hrs on 21st
No. of days without sunshine:   2   
Difference from the Monthly Mean:  106.6 %  
Cloud cover (mean at 0900):   5.1 oktas (63.8 %)
    
Pressure (reduced to sea level at 0900):    
The Highest Pressure:    1026.1 mb on 22nd
The Lowest Pressure:    994.3 mb on 7th
Mean Pressure (recorded at 0900):  1013.2 mb  
    
Winds    
Run of wind (mean over 24 hrs):  109.5 miles  
Mean daily wind speed:    5.9 mph  
Run of wind (cumulative):   3395.8 miles  
Highest Maximum Gust:   39 mph on 20th
No. of gusts of 50mph or more:   0   
Highest wind strength (at 0900):  17.3 mph on 16th
Mean wind strength (at 0900):  7.4 mph  
    
Winds from the Following Directions:    

N 0 NE 1 E 3 SE 4 S 6 SW 5 W 5 NW 7 Calm 0
    
Concrete     
Lowest Concrete Minimum:   6.6 C on 5th & 13th
Mean Concrete Minimum:   11.4 C  
    
Evaporation    
Piche      92.9 ml  
Pan      97.6 mm    

Days with:    
Thunder:     2   
Hail <5mm:    0   
Hail >/=5mm:     0   
Snow or snow & rain:    0   
Snow lying:     0   
Fog:      0   
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.