Royston (Iceni) Weather Station

Daily Weather Observations - March 2012

March 2012 Weather Review

(All differences from average quoted in this report relate to the 30 Year period 1981/2010)

The March 2012 weather continued a familiar theme of recent times, the month being warm, dry and sunny.

It was the mildest March in Royston since 1997, but even more significant was the fact that the mean daily maximum temperature of 13.6°C (2.9°C above average) was the highest in March since records began in 1972.

The mean night minimum temperature in the month was 0.4°C above average at 4.0°C. No air frosts occurred in March, the lowest night minimum temperature being 0.5°C on 26th. The lowest grass minimum temperature (-3.2°C) of the month was also recorded on this date. It was the first March with no air frost since 1997. A total of 10 ground frosts occurred in the month.

The highest temperature recorded in March was 21.6°C on 28th, making this day the equal warmest day in March since at least 1972. The other March day achieving this temperature was 17th March 1990.

The mildest night of the month was 10th with a minimum temperature of 7.5°C. The coldest day in March was 5th with a maximum temperature of the same value, 7.5°C.

The mean earth temperature at 30 cms depth as observed at 0900 GMT daily was 7.7°C, which is 1.0°C above average.

Although the warm spell at the end of March was a newsworthy event it was overshadowed by the continuing severe drought which has now lasted well over a year. March started off on a wet note when 14.0 millimetres rainfall was recorded on 4th, but this turned out to be a false dawn when dry conditions returned for the rest of the month, and no measurable rainfall at all was recorded over the period 19th to 31st.

Total rainfall in March was 20.5 millimetres, which is 52% of average. The wettest day of the month was 4th as noted above, whilst the number of "rain days" (0.2 millimetres or more) was 7, with rainfall exceeding 1.0 millimetre on 3 of these days. March 2011 was a much drier month with only 4.4 millimetres rainfall!

The cumulative total of rainfall for 2012 to the end of March stands at 85.6 millimetres, which is 66% of average.

March was a very sunny month with a sunshine total of 188.0 hours, which is 164% of average. It was the sunniest March since 2003 (197.9 hours). The sunniest day in March was 28th with 12.2 hours sunshine, but 26th, 27th and 29th also achieved sunshine totals very close to this figure with sunshine of over 12 hours.

Only 4 days (4th, 12th, 13th and 16th) in March were completely sunless.

The mean wind speed in March was 5.0 mph, and the maximum wind gust recorded was 34 mph on 7th. The highest daily (00/00 GMT) mean wind speed was 14.1 mph on 5th, and at the other end of the scale the lowest daily mean wind speed was 1.1 mph on 13th.

Winds with a westerly component accounted for about half the days in the month, with a fairly even distribution of winds across the other sectors, as per the following analysis of daily wind directions at 0900 GMT: NORTH 2 days, NE 2, E 3, SE 5, S 3, W 3, W 8, NW 5 and CALM 0.

The mean MSL air pressure was very high at 1027.1 mB, which is 12.1 mB above average. The highest and lowest air pressure values recorded in March were 1037.7 mB and 1009.0 mB on 27th and 7th respectively.

The mean relative humidity in the month was 80.9%. The highest daily (00/00 GMT) mean relative humidity was 95.2% on 12th, whilst the lowest daily mean was 52.8% on 28th. The absolute lowest relative humidity reading in March was 31% at 1555 GMT on 28th.

The number of days with fog (visibility < 1000 metres @ 0900 GMT) in March was 5 (2nd, 12th, 23rd, 24th and 25th). On 2 (12th and 23rd) of these days visibility fell below the 200 metres threshold.

Richard Barker

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

5th April 2012

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