PITSFORD HALL WEATHER STATION NORTHAMPTON, UNITED KINGDOM MONTHLY WEATHER REPORT - SEPTEMBER 2003 Headline: Another dry month with rainfall substantially below average. Also warm and reasonably sunny. A distinctly autumnal feel in the final week The month opened with high pressure influencing the scene. The county enjoyed a dry few days with some good spells of sunshine (10.9hrs on the 4th) and temperatures rose to a warm 24.7C on 4th & 5th. From the 5th onwards conditions became increasingly unsettled. A succession of depressions and associated fronts tracked across the region. Whilst rain and some thundery showers affected many parts of England and Wales, the county was to wait until the 9th before any significant rain was recorded (6.4mm over 7.1hrs). Further showers were recorded on the 10th and 11th. High pressure developed across the British Isles on the 12th remained a dominant influence over the weather until the 17th. It became very warm once again with daytime maxima typically in the mid 20s, reaching a high of 27.5C on the 17th. Good spells of sunshine were also recorded with winds remainly generally light. Despite an end to the warm conditions forecast for the 18th onwards, the cold front heralding this change became stalled over the north and west allowing the county to continue enjoying some warm and dry weather until the 22nd when the front finally worked south-eastwards bringing some fairly heavy rain (10.3mm in a little under 3 hours). With the front out of the day, high pressure regained control providing a few days of good late September sunshine. Night-time temperatures dropped markedly under clear skies, especially on the 24th with minima recorded of 3.9C, almost low enough for a ground frost at Pitsford (0.4C). A weak cold front then moved southwards on the 26th bringing occasional light showers. As the month came to a close, rain affected many parts of England and Wales, although the county escaped dry. Air Temperatures The Highest Maximum: 27.5C on 17th The Lowest Maximum: 15.4C on 23rd The Highest Minimum: 14.5C on 19th The Lowest Minimum: 3.9C on 24th The Mean Maximum: 21.2C The Mean Minimum: 9.0C The Overall Mean: 15.1C Difference from the Monthly Mean: 1.1C Relative Humidity: Highest Relative Humidity (at 0900): 92.4% on 20th Lowest Relative Humidity (at 0900): 56.1% on 15th Mean Relative Humidity (at 0900): 77.3% Dew Point: The Highest Dew Point (at 0900): 15.8C on 10th The Lowest Dew Point (at 0900): 6.3C on 23rd, 24th & 25th The Mean Dew Point (at 0900): 10.6C Rainfall: Total: 19.0mm Difference from the Monthly Mean: 33.5% Duration: 12.3hrs Highest 24 hour fall (from 0900): 10.3mm on 22nd Rain Days (>/=0.2mm): 4 Wet Days (>/=1.0mm): 3 Sunshine: Total Duration of Bright Sunshine: 176.4hrs Sunniest day: 11.4hrs on 14th Days without sunshine: 0 Cloud cover (mean at 0900): 4.4oktas (55.0%) Pressure (reduced to sea level): The Highest Pressure: 1031.9mb on 24th The Lowest Pressure: 1001.5mb on 22nd Mean Pressure (recorded at 0900): 1018.7mb Winds Run of wind (mean over 24 hrs): 78.4miles Mean daily wind speed: 4.2mph Highest daily wind speed: 9.2mph on 8th Run of wind (to date): 2350.7miles Highest Maximum Gust: 36mph on 22nd Highest wind strength (at 0900): 10.4mph on 23rd Mean wind strength (at 0900): 3.8mph Winds from the Following Directions: N 5 NE 1 E 1 SE 3 S 12 SW 0 W 1 NW 7 Calm 0 Ground Temperatures: Lowest Grass Minimum: 0.4C on 24th Mean Grass Minimum: 6.0C Lowest Concrete Minimum: 4.0C on 29th Mean Concrete Minimum: 9.2C Lowest Bare Earth Minimum: 3.5C on 24th & 25th Mean Bare Earth Minimum: 8.5C Soil/Earth Temperatures: Surface mean: 14.9 C 5cm mean: 14.0 C 10cm mean: 14.5 C 20cm mean: 15.4 C 30cm mean: 15.8 C 40cm mean: 15.9 C 50cm mean: 16.3 C 100cm mean: 16.0 C Days with: Thunder: 0 Hail less than 0.5mm: 0 Hail greater than/equal to 0.5mm: 0 Snow or snow & rain: 0 Fog: 0 Ground frost: 0 Air frost: 0 Total Evaporation (tank) 62.07mm