Royston (Iceni) Weather Station

Daily Weather Observations - March 2005

The Spring commenced with a dull but rather dry March, whilst the mean temperature for the month was a little above average.

The cold spell at the end of February carried over into March and the first week of the month was particularly cold with snowfall on 4 days and frequent night frosts. Temperatures increased considerably after mid-month, to a sufficient extent to raise the mean temperature to 0.8°C above average by the end of the month.

The following figures illustrate the sharp contrast in temperature between the two halves of the month. The mean daily maximum and minimum temperatures for the period 1^st/15^th were 7.1°C and 0.7°C respectively. The equivalent values for 16^th/31^st were 14.2°C and 7.4°C respectively!

The mean daily maximum temperature for the whole month was 10.8°C, which is 0.7°C above the 30 Year (1973/2002) average. The mean night minimum temperature was 0.9°C above average at 4.2°C. It was the mildest March since 2003 only.

The highest temperature recorded in March was 18.0°C on 18^th whilst the lowest temperature recorded was –3.6°C on 4^th. The lowest grass minimum temperature in the month, -8.5°C, also occurred on 4^th. The lowest daily maximum temperature was 3.3°C on 2^nd. The mildest night was 16^th/17^th when the minimum temperature was 11.2°C. Totals of 7 air frosts and 10 ground frosts were recorded in March.

The mean earth temperature at 30 cms depth as observed at 0900 GMT daily was 6.8°C. The earth temperature varied between a minimum of 3.0°C on 5^th and a maximum of 9.9°C on 27^th.

For the 4^th consecutive month rainfall was below average. The rainfall total of 35.9 millimetres was 84% of the 30 Year (1971/2000) average. The number of "rain days" (0.2 millimetres or more) was 16, whilst on 12 of these days rainfall reached or exceeded 1.0 millimetre.

The wettest day of the month was 26^th with 11.2 millimetres rainfall. Snow fell on 1^st, 2^nd, 4^th and 5^th, the remainder of the month being snow free. The ground was more than half covered with snow at the 0900 GMT observation hour on just 1 day (4^th) but this soon thawed as the temperature rose to a maximum of 6.5°C for the day. Hail was also observed to fall on 4^th. It was the wettest March since 2001.

Sunshine was at a premium for much of March and the fact that 25% of the month’s total occurred on just 2 days (17^th/18^th) is an illustration of this. Total sunshine in the month was 84.8 hours, which is 79% of the 30 Year (1971/2000) average. It was the dullest March since 1998. The sunniest day in March was 17^th with 10.7 hours sunshine, and this was followed by another 10.6 hours on 18^th.

March was a relatively calm month and the maximum wind gust speed in the month was a somewhat modest 41 mph on 16^th. The mean wind speed for the whole month was 3.0 mph.

The highest daily (00/00 GMT) mean wind speed was 11.5 mph on 16^th, whilst the lowest such mean value was 0.1 mph on both 19^th and 26^th.

The analysis of daily wind directions as observed at 0900 GMT is as follows: NORTH 3 days, NE 2, E 3, SE 1, S 4, SW 5, W 8, NW 3 and CALM 2.

The mean MSL air pressure in March was 1015.3 mb, which is equal to the 30 Year (1973/2002) average. The highest and lowest pressure values in March were 1034 mB and 998 mB on 9^th and 2^nd respectively.

The mean relative humidity in the month was 84.9%. The highest daily (00/00 GMT) mean relative humidity was 99.5% on 30^th whilst the lowest daily mean relative humidity was 68.7% on 14^th. The absolute lowest relative humidity reading in March was 43% at 1210 GMT on 14^th.

Fog (visibility < 1000m) was observed at the 0900 GMT observation hour on 3 days (2^nd, 19^th and 30^th) in March. On 19^th the fog was thicker and visibility fell below the 200metres threshold.

Richard Barker

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

6^th April 2005

Royston Crow (Corvus Cornix)

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