Royston (Iceni) Weather Station

Daily Weather Observations - October 2007

Royston experienced an average October as far as temperatures and sunshine are concerned but rainfall was below average.

To start with rainfall the most significant feature was that 83% of the month’s rainfall was recorded on just 2 days, the consecutive Tuesdays 9^th and 16^th. The rest of the month was essentially dry, particularly the second half. It was the driest October since 2003.

The number of "rain days" (0.2 millimetres or more) was 7, whilst on 4 of these days rainfall exceeded 1.0 millimetre. The wettest day of the month was 16^th with rainfall of 23.8 millimetres. Rainfall duration in October was 34.0 hours. No thunder was heard or hail observed to fall in the month.

Although this was the 4^th consecutive warmer than normal October it has to be said that temperatures were only just above average in October this year and in 2004. It was, in fact, the coolest October since 2004.

The mean daily maximum temperature in October was 14.9°C, which is 0.3°C above the 30 Year (1976/2005) average for Royston. The mean night minimum temperature was 0.1°C above average at 8.1°C.

The highest daily maximum temperature in the month was 18.9°C on 4^th. In contrast the lowest daily maximum temperature was 10.0°C on 25^th. The lowest night minimum and grass minimum temperatures of 1.2°C and –2.5°C respectively both occurred on 24^th. The highest night minimum temperature of the month was 13.6°C on 13^th. A total of 6 ground frosts occurred in October, but no air frost was recorded.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 12.5°C. The highest and lowest earth temperatures recorded in the month were 14.2°C and 9.5°C on 13^th and 24^th respectively.

The distribution of sunshine through the month was very uneven, illustrated by the fact that sunshine of 39.5 hours for the period 1^st/16^th was followed by sunshine of 56.2 hours over the following 7 days 17^th/23^rd. A very dull spell then followed with only 0.7 hours sunshine in the 5 days from 24^th to 28^th inclusive.

Total sunshine in October was 113.5 hours, which is 99% of the 30 Year (1971/2000) average. The sunniest day of the month was 4^th with 10.1 hours. The number of days with no sunshine at all was 6. It was the dullest October since 2004.

The mean wind speed during October was 2.5 mph. The highest daily (00/00 GMT) mean wind speed was 10.1 mph on 28^th whilst the lowest daily mean wind speed was 0.0 mph (to nearest 1 decimal place) on 2^nd, 5^th and 7^th. The maximum wind gust speed recorded in October was 44 mph on 28^th.

The analysis of wind directions as observed at 0900 GMT daily is as follows: NORTH 2, NE 4, E 0, SE 2, S 8, SW 2, W4, NW 2, and CALM 7.

The mean MSL air pressure in the month was 1020.9 mB, which is 7 mB above the 1976/2005 average. The highest and lowest pressure values in October were 1035 mB and 1007 mB on 20^th and 16^th respectively.

Relative humidity in October was fairly high with a mean value of 90.4%. The highest daily (00/00 GMT) mean relative humidity was 97.9% on 9^th whilst the lowest daily mean value was 79.4% on 4^th. The absolute lowest relative humidity reading in October was 36% at 1430 GMT on 4^th.

Although several mornings in the month were rather misty the visibility threshold (< 1000 metres) for fog at the 0900 GMT observation hour was reached on only 1 day, 26^th, in the month.

Met. Observer, Royston (Iceni) Weather Station

7^th November 2007

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