WEATHER ANALYSES FOR 2009
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MONTHLY WEATHER REVIEWS AND CLIMATOLOGICAL SUMMARIESJanuary
Headline: Anticyclonic and very cold for much of the first half of the month, becoming increasingly unsettled with frequent frontal systems bringing rain working through during the second half.
FebruaryHeadline: Bitterly cold first half with frequent heavy snowfalls. Mild, but dull second half.
Headline: A month of alternating unsettled and settled weather although becoming overall drier, warmer and sunnier than normal.
Headline: Very warm with below average rainfall. Long sunny periods, especially in the second half.
Headline: Changeable, but drier than normal with a wet unsettled spell around mid-month.
Headline: Cool and unsettled during the first half of the month, increasingly warm and humid later.
JulyHeadline: Mostly cyclonic and wet. Warm at first, but then mostly cool and breezy.
AugustHeadline: Changeable, but with most of the rain falling during the first week.
Headline: Wet at the start, but then a protracted dry spell broken only by drizzle later in the month. Warmer than usual
OctoberHeadline: More settled and anticyclonic than some recent Octobers – rainfall below average and temperatures close to the norm.
NovemberHeadline: Mildest November for 10 years. High frequency of southerly winds and rain recorded nearly every day.
Headline: A cold month – the coldest since 1995 in Northampton. Snowfall in the week before Christmas lying on the ground until Boxing Day.
CLIMATOLOGICAL STATISTICS FOR 2009
Air Temperatures The Highest Maximum: 30.0 C on 30th June The Lowest Maximum: 0.0 C on 18th December The Highest Minimum: 17.1 C on 5th August The Lowest Minimum: -6.5 C on 19th December The Mean Maximum: 14.1 C The Mean Minimum: 6.4 C The Overall Mean: 10.3 C Difference from the Yearly Mean: 0.4 C Solar Radiation (from 1st May) Maximum (at 0900): 784.0 W/m^2 on 20th June Mean (at 0900): 244.4 W/m^2 Relative Humidity: Highest Relative Humidity (at 0900): 10th,14th,19th,27th January; 18th,20th February; 13th March; 3rd April; 21st,24th,27th July; 21st, 22nd,24th-30th October; 9th-11th November; 11th,18th,22nd-25th,28th-30th December Lowest Relative Humidity (at 0900): 46.4 % on 6th July Mean Relative Humidity (at 0900): 84.3 % Dew Point: The Highest Dew Point (0900): 18.4 C on 3rd July The Lowest Dew Point (at 0900): -6.4 C on 20th December The Mean Dew Point (at 0900): 7.3 C Rainfall: Total: 509.3 mm Percentage of the Yearly Mean: 84.8 % Duration: 454.5 hrs Highest 24 hour fall (0900 to 0900): 20.9 mm on 9th February Rain Days (>/=0.2mm): 158 Wet Days (>/=1.0mm): 113 Sunshine: Total Duration of Bright Sunshine: 1407.8 hrs Sunniest day: 14 hrs on 30th May No. of days without sunshine: 55 Percentage of the Yearly Mean: 86.7 % Cloud cover (mean at 0900): 5.5 oktas Pressure (reduced to sea level): The Highest Pressure (at 0900): 1038.8 mb on 11th September The Lowest Pressure (at 0900): 972.3 mb on 23rd January Mean Pressure (at 0900): 1013.8 mb Winds Run of wind (mean over 24 hrs): 119.8 miles Mean daily wind speed: 6.5 mph Run of wind (cumulative): 43630 miles Highest Maximum Gust: 50 mph on 25th March No. of gusts of 50mph or more: 1 Highest wind strength (at 0900): 29 mph on 19th November Mean wind strength (at 0900): 8.9 mph
Winds from the Following Directions: North 31 North-east 24 East 20 South-east 43 South 87 South-west 51 West 38 North-west 54 Calm 15
Concrete Lowest Concrete Minimum: -8 C on 8th January Mean Concrete Minimum: 5.8 C Evaporation Piche 879.6 ml Pan Not available Days with: Thunder: 11 Hail <5mm: 2 Hail >/=5mm: 1 Snow or snow & rain: 19 Snow lying: 29 Fog: 17 Air Frost: 39 Duration of Air Frost: 332 hrs Gales: 0 Wettest month: 81.3 mm in July Driest month: 14.3 mm in September Warmest month: 17.1 C~ in August Coolest months: 3.0 C~ in January and December Sunniest month: 194.3 hrs in May Dullest month: 41.0 hrs in January Windiest month: 10.3 mph~ in November Calmest month: 4.4 mph~ in June ~ averages