Royston (Iceni) Weather Station

Daily Weather Observations - June 2003

The June weather was warm and sunny, with rainfall a little under average.

In fact, it was the warmest June in Royston since the memorable hot Summer of 1976. This record was achieved despite the absence of any notably high temperatures, and was attributable to the consistent warmth which was maintained throughout the month. This is illustrated by the fact that the daily maximum temperature failed to exceed the 30 Year (1973/2002) daily mean on only 2 days (6^th and 30^th) in the month. Also, these were the only 2 days in the month when the daily maximum temperature did not exceed 20°C.

The mean daily maximum temperature in June was 22.6°C, which is 2.9°C above the 30 Year (1973/2002) average. The highest daily maximum temperature recorded was 27.5°C on 16^th. This monthly maximum temperature has been exceeded in June in no less than 12 of the years since 1976. At the other end of the scale the lowest daily maximum temperature recorded was 17.6°C on 6^th.

The mean daily minimum temperature in the month was 12.4°C, which is 2.0°C above average. The lowest minimum and grass minimum temperatures in June were 8.6°C on 15^th and 5.9°C on 21^st respectively. Both these values are the highest for June in at least the last 30 years.

The earth temperature at 30 cms depth as measured at 0900 GMT daily peaked at 19.4°C on 30^th, after registering a minimum value of 16.9°C on both 7^th and 9^th. The mean earth temperature for the whole month was 18.2°C.

For the 5^th consecutive month in Royston rainfall was below average in June, although 8.6 millimetres rainfall on the last day of the month reduced the June deficit to less than 10%. Total rainfall in June was 46.2 millimetres, which is 92% of the 30 Year (1971/2000) average. It was the wettest June since 1999 despite being drier than average.

The wettest day of the month was 22^nd with 17.0 millimetres rainfall. The number of "rain days" (0.2 millimetres or more) was 14, whilst on 10 of these days the rainfall reached or exceeded 1.0 millimetre. Rainfall for the first 6 months of 2003 totalled 240.7 millimetres, the very wet January being largely responsible for this figure being as ‘high’ as 89% of average.

Thunder was heard on 3 days (2^nd, 17^th and 22^nd) in June. No hail was observed to fall in the month.

Rainfall duration in June was 30.8 hours.

As well as being dry, the first half of the year was notable for its sunshine value, this just exceeding the 1000 hour mark by the end of June, standing at 1002.5 hours, which is 32% above average. As regards June, the first week or so ran a sunshine deficit compared to the average, but then daily sunshine values picked up to raise the sunshine total for the month to 13% above average at 220.7 hours.

The sunniest day in June was 15^th with 15.5 hours sunshine. Daily sunshine also exceeded 15 hours on 13^th and 20^th. For the second month this year no completely sunless days occurred in June (the other month being April).

Winds with a southerly component were dominant in June with the directions SE, S, and SW accounting for 17 days in respect of the daily 0900 GMT observation of wind direction. The full analysis of wind directions as observed daily at 0900 GMT is as follows: NORTH 1 day, NE 1, E 3, SE 5, S 3, SW 9, W 6, NW 2, and CALM 0.

The mean wind speed in June was 3.3 mph. The highest daily (00/00 GMT) mean wind speed in the month was 8.0 mph on 19^th, whilst the lowest daily mean wind speed was 0.4 mph on 15th. The highest wind gust speed recorded in June was 44 mph on 19^th.

The mean MSL air pressure was approximately 2 mB below normal at 1015.2 mB. The highest and lowest air pressure values recorded in June were 1025 mB on 13^th and 999 mB on 30^th respectively.

As might be expected the mean relative humidity value of 71.6% in June was the lowest for any month so far this year, but rather surprisingly only 0.6% below the corresponding April figure. The highest daily (00/00 GMT) mean relative humidity was 86.6% on 30^th, and the lowest mean daily relative humidity was 56.9% on 13^th. The absolute lowest relative humidity value in the month was 31% at 1330 GMT on 13^th and 1040 GMT on 29^th.

Fog (visibility < 1000 metres) was not recorded at the 0900 GMT observation hour on any day in June.

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

4^th July 2003

Royston Crow (Corvus Cornix)

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