Royston (Iceni) Weather Station

Daily Weather Observations - February 2003

It was a dry and very sunny February in Royston, with an about average mean temperature.

Despite a very dull spell from 6^th to 12^th inclusive, in which only 4.4 hours sunshine was recorded, and none at all from 9^th to 12^th, February still managed to achieve a sunshine total of 120.8 hours, making it the sunniest February in Royston since 1998.

The 12 day period from 14^th to 25^th, which accumulated 82.4 hours sunshine, was largely responsible for the high sunshine total for the month, which was 175% of the 30 Year (1961/1990) average.

The sunniest day of February was 21^st with 9.4 hours sunshine. The number of days in the month which were completely sunless was 5 (6^th, and 9^th/12^th as stated above).

After the very wet January the weather in February became much drier, and very dry between 13^th and 27^th. In this 15 day period only 0.2 millimetres rainfall was recorded. The rainfall total for the month was 16.6 millimetres, which is 47% of the 30 Year (1971/2000) average. It was the driest February since 1998, when rainfall was only one quarter of this year’s figure! On average February is the driest month of the year in Royston, so this year more closely followed its normal character after being wet or very wet in the previous 3 years.

The highest daily rainfall in February was 3.8 millimetres on both 8^th and 11^th. The number of "rain days" (0.2 millimetres or more) in the month was 10, whilst 6 of these days were classified as ‘wet’ days with rainfall exceeding 1.0 millimetre. Rainfall duration in February was 38.2 hours.

The month commenced with a 12 cm residual level snow cover from the snowfall on 30^th January, but a thaw in progress reduced this depth to 5 cm at 0900 GMT on 2^nd, and none at all on 3^rd (although a few pockets of snow remained in the Royston area for several days afterwards). Actual snowfall in February was minimal with only small quantities falling on 1^st and 4^th, whilst hail was observed to fall on just 1 day (2^nd).

For recent times February became a relatively unusual month with a below average mean temperature, but by only 0.1°C! A frosty spell in the 3^rd week of the month pegged the mean temperature back to near normal, and over the month as a whole 11 air frosts and 16 ground frosts occurred. Air frost duration in February was 128.8 hours.

The mean daily maximum temperature in February was 7.6°C, which is 0.4°C above the 30 Year (1973/2002) average. The mean night minimum temperature was in contrast 0.6°C below average at 1.2°C. The highest temperature recorded in the month was 13.5°C on 27^th, whilst the lowest temperature recorded was –6.1°C on 18^th. This was the lowest temperature recorded in February since 10^th February 1991, and the lowest temperature recorded in any month since 3^rd January 1997.

The lowest day maximum temperature in February was 2.6°C on 13^th, whilst the highest night minimum temperature was 7.0°C on 8^th. Despite the mean temperature being close to the average it was nonetheless the coldest February in Royston since 1996.

The mean earth temperature at 30 centimetres depth as measured at 0900 GMT daily was 3.5°C. Highest and lowest earth temperature values in the month were 5.4°C on 12^th and 13^th, and 2.0°C on 21^st, 22^nd, and 23^rd, respectively.

The monthly analysis of wind directions as observed at 0900 GMT daily was NORTH 1 day, NE 2, E 4, SE 6, S 6, SW 4, W 2, NW 1 and CALM 2.

The mean wind speed in February was 3.3 mph. The highest wind gust recorded was 39 mph, on both 3^rd and 28^th. The highest and lowest daily (00/00 GMT) mean wind speeds were 9.5 mph and 0.3 mph on 3^rd and 12^th respectively.

The mean air pressure reduced to mean sea-level was 1019.6 mB, which is approximately 3 mB above average. The highest air pressure value in the month was 1041 mB on 17^th, and the lowest air pressure value was 991 mB on 3^rd.

The mean relative humidity in the month was 86.2%, ranging from a highest daily (00/00 GMT) mean of 98.5% on 12^th to a lowest daily mean of 74.4% on 25^th. The absolute lowest relative humidity reading in February was 51% at 1345 GMT on 18^th.

Fog was recorded at the 0900 GMT observation hour on 3 days (12^th, 22^nd and 24^th ) in February, with visibility falling below the 200 metres threshold on each occasion.

Summary details for the Winter (December/February) 2002/2003 season conclude this report. The mean daily maximum temperature in Winter was 7.3°C, which is 0.3°C above average. The mean Winter night minimum temperature was 2.6°C, which is also 0.3°C above average. Total rainfall was 143% of average at 198.1 millimetres, whilst the Winter sunshine total was 218.7 hours (128% of normal). It was both the coldest and wettest Winter since 2000/2001 only.

Richard Barker

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

6^th March 2003

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