Royston (Iceni) Weather Station
Daily Weather Observations - August 2003
August 2003 Weather Review
The August 2003 weather in Royston can be summarised as very warm, very dry and very sunny!
August was a record breaking month for both temperatures and rainfall. The highest temperature record for any month of the year (since observations commenced at Royston (Iceni) Weather Station on 1st May 1972) was broken twice in the space of 4 days. The existing highest temperature record stood at 35.0°C on 3rd August 1990, but on 6th August the temperature crept just past this value to 35.1°C., and then on 10th August the mercury rose to an amazing 36.4°C (at 1305 GMT). If conditions had remained perfectly clear it is likely an even higher value would have been achieved, but in the event advancing cloud checked any further rise in temperature.
The high temperatures experienced in the first 2 weeks of August reduced considerably in the second half of the month and day maximum temperatures even dipped below average values on several days, particularly near the end of the month. What had promised to be a record breaking mean temperature for the month as a whole did not materialise and it was the hottest August since 1997 only (but was nonetheless the 5th hottest month of any in the last 30 years).
The mean daily maximum temperature in August was 25.7°C, which is 3.4°C above the 30 Year (1973/2002) average for Royston, whilst the mean night minimum temperature was 1.3°C above average at 13.9°C.
The lowest temperature recorded in the month was 6.9°C on 30th, and the lowest grass minimum temperature was 4.3°C on 31st. On the night of 9th/10th the minimum temperature was no lower than 19.8°C, and as well as making for an uncomfortable night it provided a springboard for the highest temperature record achieved later that day (see above). The lowest day maximum temperature recorded in August was 19.2°C on 28th.
The mean earth temperature at 30 cms depth as measured at 0900 GMT daily was 20.2°C, reaching a maximum of 22.5°C on 12th, and falling to a minimum of 17.1°C on 31st.
The extremely dry conditions in August also made the headlines since it was the driest August since 1947, and the 3rd driest month of any (after August 1947 and February 1891) since the Royston rainfall record began on 1st January 1853.The only measurable rainfall which occurred in August was on 1st, and this was only 0.7 millimetres. This amount thus becomes the total for the month and is just 1.4% of the 1971/2000 average. The lack of any further rainfall, apart from a few spots on several days, in August created very dry and dusty conditions in the Royston area by the end of the month. The situation has been exacerbated by the dry nature of the year generally, after the wet January. Rainfall duration in August was 1.5 hours. Thunder was heard on just 1 day (10th) in August.
After a sunless day on 1st, abundant sunshine was in evidence over the following two weeks or so and the normal sunshine amount for August had been reached by 18th. This suggested the month could be heading for a record breaking total to match the temperature and rainfall anomalies, but a relatively dull last week ‘restricted’ the final sunshine total to 239.2 hours, which is 135% of the 1961/1990 average.
This is nonetheless a very high total for any month in Royston and it was, in fact, the highest monthly sunshine total since July 1999. The highest daily sunshine amount was 14.3 hours, and this occurred on both 2nd and 3rd. No fewer than 9 other days in the month registered more than 10 hours sunshine.
August was a relatively calm month and the highest wind gust speed measured was 30 mph on 21st. The mean wind speed for the month as a whole was 2.1 mph, the lowest such value for any month so far this year.
The highest daily (00/00 GMT) mean wind speed in August was 6.5 mph on 22nd, whilst the lowest daily mean wind speed was 0.6 mph on both 26th and 27th. The analysis of daily wind directions as observed at 0900 GMT shows a relative lack of winds containing a southerly component, as per the following: NORTH 3 days, NE 8, E 1, SE 3, S 2, SW 2, W 7, NW 5 and CALM 0.
The mean air pressure reduced to mean sea-level in August was 1018.7 mB, which is approximately 1.5 mB above average. The highest and lowest pressure values in the month were 1025 mB and 1005 mB on 5th and 29th respectively.
The absolute lowest relative humidity reading in August was 19% at 1240 GMT on 10th. The mean relative humidity for the month was 67.5%. The highest and lowest daily (00/00 GMT) mean relative humidity values were 92.2% and 53.1% on 1st and 10th respectively.
As regards the Summer (June/August) season as a whole it has been the hottest Summer in Royston in at least the last 30 years, although the mean temperature was only 0.2°C higher than in the memorable hot Summer of 1976. Additionally, it was the driest Summer since 1995. The mean daily maximum temperature in Summer was 24.0°C, which is 2.6 °C above the 30 Year (1973/2002) average. The mean night minimum temperature was 1.5°C above average at 13.3°C. Total rainfall was 94.6 millimetres (66% of average), and total sunshine was 662.9 hours (119% of average).
Richard Barker
Richard Barker
Met. Observer, Royston (Iceni) Weather Station
5th September 2003
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