Royston (Iceni) Weather Station

Daily Weather Observations - June 2008

Temperatures and sunshine were slightly ahead of the long term averages in June, but it was a drier than average month overall.

Despite the mean temperature in June being 0.4°C above average it was, in fact, the coolest June since 2001 (although the mean temperature was equal to the 2002 value).

The absolute maximum temperature in the month of 25.8°C (on 9^th) was unexceptional for June and has been exceeded in June in 26 of the years since 1972. The lowest night minimum temperature was 6.4°C on 16^th. The lowest grass minimum temperature in June of 2.7°C also occurred on this date.

In contrast to these extremes the lowest day maximum temperature in June was 14.9°C on 3^rd, whilst the highest night minimum temperature was 16.3°C on 28^th.

The mean daily maximum temperature in June was 20.1°C, which is 0.2°C above the 30 Year (1976/2005) average. The mean night minimum temperature was 0.5°C above average at 11.1°C.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 17.0°C. The highest and lowest earth temperature values in the month were 18.4°C and 15.5°C on 29^th and 4^th respectively.

Moving on to rainfall it was the 8^th drier than average June in the last 9 years. Total rainfall was 38.5 millimetres, which is 77% of the 1971/2000 average. The number of "rain days" (0.2 millimetres or more) in June was 10, with 8 of these days receiving more than 1.0 millimetre rainfall.

The wettest day in June was 3^rd with 11.9 millimetres rainfall. Rainfall duration in the month was 51.3 hours. It was the first June without thunder since 1995, and only the 3^rd June without thunder since records commenced at Royston (Iceni) Weather Station in 1972.

The distribution of sunshine was somewhat uneven in the two halves of June. Sunshine for 1^st/15^th was 84.4 hours, but the equivalent figure for 16^th/31^st showed a significant increase to 122.6 hours. Total sunshine in June of 207.0 hours was 115% of the 1971/2000 average. It was the sunniest June since 2006 only (which was a very sunny June with sunshine of 258.5 hours).

The sunniest day in June was 9^th with 15.4 hours sunshine. The number of completely sunless days in June was 3 (3^rd, 7^th and 21^st).

The second half of June was rather windy for a Summer month and this resulted in the mean wind speed for the whole month increasing to 5.0 mph. The windiest day of the month was 22nd with a mean 24 hour (00/00 GMT) wind speed of 12.6 mph. Surprisingly this was also a very sunny day with 12.8 hours sunshine recorded. At the other end of the scale the calmest days of the month were 1^st and 2^nd, both with a mean wind speed of 0.5 mph.

The daily distribution of wind directions (at 0900 GMT) was as follows: NORTH 3 days, NE 3, E 0, SE 2, S 1, SW 3, W 11, NW 7 and CALM 0.

The mean MSL air pressure in June was 1013.0 mB, which is 4 mB below the 1976/2005 average. The highest daily (00/00 GMT) pressure value recorded in the month was 1023 mB on 9^th, whilst the lowest such value was 1000 mB on 19^th.

The mean relative humidity in June was 77.0%. The highest and lowest daily (00/00 GMT) mean relative humidity values were 99.9% and 64.5% on 3^rd and 9^th respectively. The absolute lowest relative humidity reading in June was 27% at 1605 GMT on 5^th. The relative humidity fell to near this value on 17^th also, with 28% recorded at 1715 GMT.

Fog (visibility < 1000 metres at 0900 GMT) was observed on just 1 day (3^rd) in June.

Met. Observer, Royston (Iceni) Weather Station

5^th July 2008

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