Royston (Iceni) Weather Station
Daily Weather Observations - June 2000
JUNE 2000 WEATHER REVIEW
It was a dry and warmer than average June in Royston, with sunshine not far from average.
The familiar theme of the last few years was maintained in June with yet another warmer than average month, in fact the 34th month with an above average mean temperature in the 42 months from January 1997.
A short-lived heat-wave from 17th to 19th June produced the hottest day for nearly 5 years in Royston with a maximum temperature of 32.0°C on 19th. This was the highest temperature recorded in any month since 2nd August 1995, and the highest temperature in June since 28th June 1976. This latter date occurred in the remarkable heat-wave of 23rd June to 8th July 1976 when the temperature reached or exceeded 30°C on 16 consecutive days.
The next day, 20th June, saw temperatures begin to return to more normal values with a 10°C drop, and by 24th a maximum temperature of only 15.9°C was recorded.
The mean daily maximum temperature in June was 20.7°C, which is 1.0°C above the 25 Year (1973/1997) average. The temperature reached or exceeded 20°C on 14 days in the month. The mean night minimum temperature was 11.9°C, which shows a greater positive anomaly at 1.7°C above average. Overall it was the warmest June in Royston since 1992.
The lowest temperature recorded in June was 7.8°C on 7th, this date also seeing the lowest grass minimum temperature in the month of 5.0°C. The lowest day maximum temperature was 15.7°C on 5th.
The mean earth temperature at 30 centimetres depth as measured at 0900 GMT daily was 17.7°C. The earth temperature commenced the month at its lowest point of 15.3°C on 1st and rose to a maximum for the month of 20.7°C on 20th.
After the wet months of April and May, the dry June was not altogether unexpected even though June in the previous 3 years had been wet or very wet. Total rainfall of 19.7 millimetres was only 41% of the 35 Year (1961/1995) Royston average.
The number of "rain days" (0.2 millimetres or more) was 6 and the highest 24 hour rainfall was 6.9 millimetres, recorded on 6th. It was the driest June since 1996.
Although not strictly relevant until next month’s report, it is worth noting that the dry weather of June came to an abrupt end with rainfall of 48.9 millimetres being recorded in the first 4 days of July, an amount which equals the average for the whole of the month!
Rainfall duration in June was low as might be expected at 14.3 hours. Thunder was heard on just 1 day, 6th, whilst the only occasion hail was observed to fall was on this date also.
The dry nature of June was not reflected in increased sunshine values, however, and the month’s total sunshine duration of 183.8 hours was 6% below normal. This was despite only one day, 29th, being completely sunless ( although there was only 1 minute of sunshine on 24th and 6 minutes on 5th). In fact, the last three days of the month could only manage 1.4 hours sunshine between them so could be said to be largely responsible for June’s sunshine deficiency.
In complete contrast the 3 days 17th/19th saw a sunshine total of 44.1 hours. The middle day, 18th, was the sunniest day of the month with 15.6 hours sunshine.
June was not a particularly windy month in Royston, with an overall mean wind speed of 4.3 mph. The windiest day was 22nd with a mean wind speed of 9.4 mph, and the calmest day was 30th with a mean wind speed of 0.7 mph. The maximum wind gust speed of 37 mph was recorded on both 21st and 22nd.
The wind direction distribution for the month as observed at 0900 GMT daily was N 2, NE 1, E 0, SE 3, S 6, SW 9, W 6, NW 2, and CALM 1.
The mean MSL air pressure in June was 1018.1 mb, which is about average. The highest pressure value recorded was 1028 mb on 16th, and the lowest 1007 mb on 9th.
The mean relative humidity for the month was 74.5%. The highest and lowest daily (00/00 GMT) mean relative humidity values were 90.1% on 30th and 57.3% on 18th respectively.
The mean cloud cover in June as observed at 0900 GMT daily was 68%.
Richard Barker
Richard Barker
Met. Observer, Royston (Iceni) Weather Station
6th July 2000
Royston Crow (Corvus Cornix)
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