July was another very wet month, and not surprisingly was also cooler and duller than normal.

Although no rain at all was recorded in the 8 day period from 21^st to 28^th inclusive this interlude came after an exceedingly wet first half of July (1^st/16^th) when rainfall totalled 116.8 millimetres. By the end of the month this total had increased to 136.4 millimetres, which is 265% of average.

It was the wettest July in Royston since 1950. The number of "rain days" (0.2 millimetres or more) in July was 21, whilst rainfall exceeded 1.0 millimetre on 16 of these days. The wettest day of the month was 13^th with 33.7 millimetres rainfall. This made it the wettest day in any month since 25^th August 2010.

Even more significant than the very high July rainfall total is that the 4 months April/July 2012 have been easily the wettest such period in the Royston rainfall record which goes back to 1853. The rainfall total in this period was 439.6 millimetres, whilst the next wettest April/July period was in 1903 when rainfall totalled 397.0 millimetres. Total rainfall for January to July 2012 was 525.0 millimetres, which is 162% of average.

Despite being a very wet month, July was almost thunder free with thunder being heard on just 1 day (29^th).

Temperatures by day were generally depressed for the first 3 weeks of July and at the end of this period day maximum temperatures were running some 3°C below normal. The following 7 days were much warmer and the highest temperature of the month, 29.7°C, was recorded on 25^th. In contrast to this hot day, the lowest day maximum temperature of the month was 15.7°C on 14^th. The mean daily maximum temperature in July was 21.1°C, which is 1.6°C below average.

With the increased cloud cover this July night temperatures fared better and the mean night minimum temperature over the whole month was only 0.4°C below average at 12.5°C. The lowest night minimum temperature in the month was 8.7°C on 21^st, whilst the lowest grass minimum temperature of the month was 6.5°C, also on 21^st. The highest night minimum temperature in July was 15.8°C on 5^th. July was slightly warmer than July last year, but in the event was the ‘warmest’ July since 2010 only.

The mean earth temperature at 30 cms depth as observed at 0900 GMT daily was 18.3°C, which is 0.7°C below average. The earth temperature ranged between a ‘high’ of 20.6°C on 27^th and a ‘low’ of 17.0°C on 21^st.

For much of July sunshine was in short supply and for the period 1^st/20^th only 67.4 hours was registered, which is only 60% of the average for this period. Then in the following 6 days from 21^st to 26^th inclusive 80.2 hours sunshine was recorded! This helped to raise the total for the month to 177.4 hours, which is 91% of average. It was the sunniest July since 2009.

The sunniest day of the month was 23^rd with 15.2 hours sunshine. Despite being a dull month no day in July was completely sunless, although 3^rd came close with only 1½ minutes sunshine.

The mean wind speed in July was 5.7 mph and the maximum wind gust speed recorded was 34 mph on 16^th. The windiest day (00/00 GMT) in the month was 16^th with a mean wind speed of 9.9 mph, whereas the calmest day of the month was 21^st with a mean wind speed of 2.0 mph.

The analysis of wind directions as observed at 0900 GMT daily gives the following results: NORTH 2 days, NE 3, E 0, SE 1, S 5, SW 7, W 10, NW 3 and CALM 0.

The mean MSL air pressure in July was 1012.5 mB, which is 3.9 mB below average. The highest and lowest air pressure values recorded in the month were 1026.6 mB and 998.2 mB on 22^nd and 13^th respectively.

The mean relative humidity in July was 81.6%. The highest daily (00/00 GMT) mean relative humidity was 95.1% on 8^th, whilst the lowest daily mean relative humidity was 59.2% on 23^rd. The absolute lowest relative humidity reading in the month was 28% at 1635 GMT on 23^rd.

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

Met. Observer, Royston (Iceni) Weather Station

6^th August 2012