Royston (Iceni) Weather Station
Daily Weather Observations - June 2012
June 2012 Weather Review
(All differences from average quoted relate to the 30 Year period 1981/2010)
For the first month of Summer the June weather was poor, being cool, very wet and dull.
The June weather was dominated by a series of depressions being steered close to and over the British Isles by a jet stream displaced much further south than is normal at this time of the year. One effect of this is that it was a very wet June with a rainfall total of 125.1 millimetres, which is 262% of average.
This resulted in the month being the wettest June in Royston since 1997. In the Royston rainfall record which goes back to 1853 only 6 Junes have been wetter than this year. Surprisingly for such a wet Summer month there was a complete absence of thunder in June.
The wettest day in June was 10th with 24.3 millimetres rainfall making it the wettest June day since 6th June 1985. The number of “rain days” (0.2 millimetres or more) in June was 19, with rainfall exceeding 1.0 millimetre on 17 of these days.
June was the 3rd consecutive wet month after the long drought experienced by much of the country. The current wet spell, which commenced in mid-April, has raised the rainfall total for the first 6 months of the year to 388.8 millimetres, which is 143% of average.
The lack of any settled anticyclonic weather in June and the consequent duller than normal conditions had a detrimental effect on temperatures, particularly by day. The mean daily maximum temperature of 18.7°C in June was 1.5°C below average, but the increased cloud cover at night resulted in the mean night minimum temperature being only 0.1°C below average at 10.7°C. It was the coolest June in Royston since 1995.
The highest day maximum temperature recorded in June was 28.3°C on 28th. In contrast the lowest day maximum temperature in the month was 10.7°C on 3rd, a temperature which is not uncommon in January! The lowest night minimum temperature in the month was 5.4°C on 13th and the lowest grass minimum temperature in June was 2.7°C, also on 13th. The highest night minimum temperature in June was 17.1°C on 27th.
The mean earth temperature at 30 cms depth as observed at 0900 GMT daily was 16.0°C, which is 1.2°C below average. The highest and lowest earth temperature values recorded in June were 18.9°C and 13.8°C on 29th and 13th respectively.
The first half of June was particularly dull and by mid-month only 50.0 hours sunshine had been recorded. The second half of June saw an improvement with 102.6 hours sunshine between 16th and 30th. The month’s sunshine total of 152.6 hours was only 83% of average making it the dullest June since 1998 (which had 17.6 hours less sunshine than June this year).
The sunniest day in June was 19th with 12.2 hours sunshine. Only 2 days (3rd and 11th) in the month were completely sunless. Sunshine in March this year was 35.4 hours higher than in June!
June was a gusty month at times and the mean wind speed for the month as a whole was 6.9 mph. The maximum wind gust speed recorded was 39 mph on 8th. The windiest day of June was 8th with a 24 hour (00/00 GMT) mean wind speed of 16.3 mph, whilst the calmest day of the month (13th) experienced a mean wind speed of only 1.8 mph.
The analysis of wind directions as observed at 0900 GMT daily was as follows: NORTH 2 days, NE 2, E 2, SE 4, S 5, SW 11, W 2, NW 2, and CALM 0.
The mean MSL air pressure in June was 1010.4 mB, which is 6.4 mB below average. The highest and lowest pressure values in June were 1019.8 mB and 990.7 mB on 26th and 8th respectively.
The mean relative humidity in the month was 81.0%. The highest daily (00/00 GMT) mean relative humidity was 98.5% on 11th, whereas the lowest daily mean relative humidity was 70.5% on 19th. The absolute lowest relative humidity reading in June was 43% at 1135 GMT on 20th.
Fog (visibility < 1000 metres @ 0900 GMT) was not observed on any day in June.
Richard Barker
Richard Barker
Met. Observer, Royston (Iceni) Weather Station
5th July 2012
Royston Crow (Corvus Cornix)
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