Royston (Iceni) Weather Station

Daily Weather Observations - March 2009

After the snow in February and the colder than average Winter overall, the weather then provided some compensation with a mild, sunny and dry March.

Temperatures in March were unexceptional and it was the mildest March since 2007 only. The highest temperature recorded in the month was 16.6°C on 16^th. This value is 5°C below the highest temperature recorded in March over the last 37 years in Royston. On 17^th March 1990 a temperature of 21.6°C was attained.

The lowest temperature recorded in March was –1.7°C on 5^th. A lower absolute minimum temperature has been recorded in March in 21 of the last 37 years. The lowest grass minimum temperature in March was –5.5°C, also on 5^th. Totals of 3 air frosts and 13 ground frosts occurred in March. Air frost duration in March was 12.3 hours.

The mean daily maximum temperature in March was 12.1°C, which is 1.7°C above the 30 Year (1976/2005) average. The mean night minimum temperature was 0.1°C above average at 3.6°C.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 7.1°C. The highest earth temperature value in the month was 8.3°C on 23^rd, whilst the lowest earth temperature was 5.4°C on both 6^th and 7^th.

It was a drier than average March, the driest March since 2004, and the 7^th drier than average March in the last 8 years, in fact. Total rainfall in the month was 31.6 millimetres, which is 74% of the 1971/2000 average for Royston.

The number of "rain days" (0.2 millimetres or more) in March was 12, with rainfall equalling or exceeding 1.0 millimetre on 10 of these days. The wettest day in the month was 3^rd with 9.9 millimetres rainfall. Rainfall duration in March was 26.1 hours.

The only snowfall observed in March consisted of a few flakes in a shower in the afternoon of 8^th. Hail was observed to fall on 4 days (8^th, 25^th, 26^th and 28^th) in the month.

Although March was a very sunny month the sunshine total was still as much as 35.6 hours below the exceptional total recorded in March 2003. It was the sunniest March since 2003, however.

Total sunshine in March was 162.4 hours, which is 152% of the 1971/2000 average. The sunniest day of the month was 18th with 11.4 hours sunshine. This was the sunniest March day since 31^st March 2003. Also, it was the first March since at least 1997 with NIL days of no sunshine.

March was fairly breezy at times but there were no damaging winds which can occur at this time of the year (e.g. a wind gust of 71 mph occurred on 20^th March 2004). The mean wind speed in March was 5.9 mph, whilst the maximum gust speed recorded was 48 mph on 3^rd.

The highest daily (00/00 GMT) mean wind speed was 13.4 mph on 23^rd. At the other end of the scale the lowest daily mean wind speed was 1.0 mph on 31^st.

Winds with a westerly component dominated the month as indicated by the following table of wind directions as observed at 0900 GMT daily: NORTH 1 day, NE 1, E 2, SE 1, S 2, SW 4, W 12, NW 8, and CALM 0.

The mean MSL air pressure in March was 1012.0 mb, which is 3 mB below the 1976/2005 average. The highest and lowest air pressure values recorded in March were 1035 mB and 976 mB on 17^th and 4^th respectively.

The mean relative humidity in the month was 81.4%. The highest daily (00/00 GMT) mean relative humidity was 94.2% on 10^th, whilst the lowest daily mean relative humidity value was 70.0% on 24^th. The absolute lowest relative humidity reading in March was 33% at 1505 GMT on 24^th.

Fog (visibility < 1000 metres at the 0900 GMT observation hour) was observed on just 1 day (19^th) in March. The fog on this day reduced visibility to below the 200 metres threshold.

Met. Observer, Royston (Iceni) Weather Station

5^th April 2009

Royston Crow (Corvus Cornix)

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