August followed the trend set in July, with temperatures, rainfall and sunshine all being below average!

It was a cooler than average August with temperatures being very similar to, but marginally higher than, August last year. In the event no records were broken, it being the warmest August since 2009 only.

The mean daily maximum temperature in August was 21.2°C, which is 1.2°C below the 30 Year (1981/2010) average. The mean night minimum temperature was 0.5°C below average at 12.4°C.

A brief 3 day hot spell occurred at the beginning of the month and the highest temperature of the month, 29.8°C, was recorded on 3^rd. On 4^th the day maximum temperature dropped back to a below average 20.0°C.

At the other end of the scale the lowest day maximum temperature was 14.1°C on 18^th. This contrasts with the highest night minimum temperature in the month which was 16.0°C on both 2^nd and 3^rd.

The lowest night minimum temperature in August was 8.7°C on 19^th whilst the lowest grass minimum temperature of the month, 6.0°C, also occurred on this date.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 17.6°C. The earth temperature peaked at 20.4°C on 4^th and fell to its lowest value in the month of 15.7°C on 30^th.

Although rainfall in August was only 10% below average it was nonetheless the driest August since the exceptionally dry August of 2003 (when rainfall of only 0.7 millimetres was recorded). All intervening years experienced a wetter than average August.

Total rainfall in August was 50.7 millimetres (compared with 149.3 millimetres rainfall in August last year). The number of "rain days" in the month was 16, whilst rainfall exceeded 1.0 millimetre on 10 of these days.

The wettest day of the month was 18^th with 10.6 millimetres rainfall. Thunder was heard on just 1 day (3^rd) in August.

The most significant sunshine event of the month occurred on 23^rd when absolutely no sunshine was recorded! This was the first completely sunless day since 16^th March 2011, giving a continuous sequence of 159 days with at least some sunshine, seemingly a long such period for anywhere in the British Isles.

Total sunshine in August was 133.6 hours, which is only 71% of the 30 Year (1971/2000) average. Even so, this low sunshine total was 13 hours higher than in August last year. The sunniest day in August was 19^th with 11.5 hours sunshine. The only sunless day in the month was 23^rd, as noted above.

The mean wind speed in August was 5.6 mph and the maximum wind gust speed recorded was 33 mph on 27^th. The highest daily (00/00 GMT) mean wind speed was 10.0 mph on 8^th, whilst the lowest daily mean wind speed was 1.4 mph on 31^st.

The analysis of daily wind directions as observed at 0900 GMT shows a strong bias towards winds with a westerly component, as follows: NORTH 1 day, NE 4, E 0, SE 1, S 3, SW 9, W 10, NW 3 and CALM 0.

The mean MSL air pressure in the month was 1012.3 mB, which is 3.6 mB below the 30 Year (1981/2010) average. The highest and lowest air pressure values recorded in August were 1025.7 mB on 10^th and 999.7 mB on 6^th respectively.

The mean relative humidity in August was 77.0%. The highest daily (00/00 GMT) mean relative humidity was 96.0% on 26^th and the lowest daily mean relative humidity was 60.3% on 1^st. The absolute lowest relative humidity reading in the month was 36% at 1445 GMT on 15^th.

Fog (visibility < 1000 metres @ 0900 GMT) was not observed on any day in August.

SUMMER (June/August) 2011: Although the mean temperature in Summer was only 0.7°C below average this is a significant difference in the context of the whole Summer and in the event it was the coolest Summer in Royston since 1993. A 5% deficit of rainfall resulted in it being the driest Summer since 2005. This did not make up for the exceptionally dry Spring and rainfall for 2011 to the end of August was 281.6 millimetres, which is 26% below the 30 Year (1981/2010) average.

The mean daily maximum temperature in Summer was 21.1°C, which is 0.7°C below average. The mean night minimum temperature was also 0.7°C below average at 11.5°C. Total rainfall in Summer was 148.2 millimetres, which is 95% of the 30 Year (1981/2010) average. The Summer sunshine total of 517.5 hours was 93% of the 30 Year (1971/2000) average.

Met. Observer, Royston (Iceni) Weather Station

8^th September 2011