Royston (Iceni) Weather Station

Daily Weather Observations - August 2007

It was a cool and wet August in Royston, but with average sunshine.

Although the mean temperature was only 0.9°C below average it was, in fact, the coolest August since 1993 illustrating perhaps the warm nature of August in most of the intervening years. This warm sequence appears to have come to a temporary end at least since it was the 3^rd successive cooler than average August.

Also, it was only the 3^rd August in the last 13 years in which the temperature did not reach 30°C. The highest temperature recorded this August was 29.8°C on 5^th whilst in contrast on 22^nd the lowest day maximum temperature of the month,14.6°C, occurred. The coldest night of the month was 9^th/10^th when the lowest minimum and grass minimum temperatures of 8.5°C and 5.0°C respectively were recorded. The highest night minimum temperature of the month was 16.0°C on 14^th/15^th.

The mean daily maximum temperature in August was 21.3°C, which is 1.1°C below average, whilst the mean night minimum temperature was 0.6°C below average at 12.1°C. The mean earth temperature at 30 cms depth as observed at 0900 GMT daily was 18.1°C. The highest and lowest earth temperature values in August were 19.7°C and 16.4°C on 6^th and 24^th/25^th respectively.

All but 0.5 millimetre of the August rainfall was recorded between 12^th and 23^rd inclusive and this wet spell resulted in the rainfall total for the month of 73.0 millimetres being 47% above the 30 Year (1971/2000 average). The wettest day of the month was 19^th with 17.8 millimetres rainfall. Although not a particularly high daily rainfall total it was nonetheless the wettest August day since 1999 (but equalled in August 2000).

The number of "rain days" (0.2 millimetres or more) in August was 13 whilst on 9 of these days rainfall exceeded 1.0 millimetre. Thunder was heard on just 1 day (15^th).

Although it was a cool and wet August, sunshine managed to keep up with the 30 Year (1971/2000) average. Total sunshine in August was 190.8 hours, which is 102% of normal. The sunniest day of the month was 5^th with 14.0 hours sunshine. The number of days in August which were completely sunless was 4, which all occurred in the aforementioned wet spell.

The mean wind speed in August was 2.1 mph and the maximum wind gust speed recorded was 37 mph on 15^th. The highest daily (00/00 GMT) mean wind speed in the month was 6.2 mph on both 14^th and 15^th. The lowest daily mean wind speed was 0.1 mph on 28^th.

An analysis of wind directions as observed daily at 0900 GMT gives the following result: NORTH 8 days, NE 1, E 0, SE 0, S 3, SW 7, W 4, NW 8 and CALM 0.

The mean MSL air pressure in August was 1012.7 mB, which is approximately 4 mB below the 30 Year (1976/2005) average. The highest and lowest pressure values recorded in August were 1027 mB and 990 mB on 26^th and 14^th respectively.

The mean relative humidity in the month was 78.7%. The highest daily (00/00 GMT) mean relative humidity was 99.9% on 21^st (one of several very dull and damp days in the cool northerly spell from 19^th to 24^th). The lowest daily mean relative humidity was 59.1% on 1^st. The absolute lowest relative humidity reading in August was 27% at 1505 GMT on 5th.

Fog (visibility < 1000 metres @ 0900 GMT) was observed on 2 days (21^st and 24^th) in August.

SUMMER (June/August) 2007:

Although the Summer has attracted wide publicity for being very wet over many parts of the country it has been the wettest Summer in Royston since last year only! Total rainfall was 191.2 millimetres, which is 134% of the 1971/2000 average. However, adding May to the Summer to give a 4 month period for May/August the rainfall total of 338.7 millimetres was the highest since 1958.

As well as being wet the Summer was the coolest in Royston since 1998, but the mean temperature was only 0.2°C below average. The mean daily maximum temperature in Summer was 21.0 °C, which is 0.5°C below average. The mean night minimum temperature was 0.1°C above average at 12.1°C.

Total sunshine in Summer was 537.6 hours, which is 96% of normal. It was the dullest Summer in Royston since 2002.

Met. Observer, Royston (Iceni) Weather Station

6^th September 2007

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