Royston (Iceni) Weather Station

Daily Weather Observations - October 2010

The lowest night minimum temperature in the month was –0.1°C on 25^th, and the lowest grass minimum temperature (-3.4°C) of the month was also recorded on this date. Although the former value just gave an air frost it is likely that lower lying parts of Royston and on the South Cambridgeshire plain experienced a minimum temperature slightly lower than this. An air frost has been registered in October in only 6 previous years since 1972. A total of 5 ground frosts was recorded this October.

The highest night minimum temperature in October was 14.0°C on 9^th, whilst the lowest day maximum temperature recorded was 8.9°C on 25^th (which was perhaps surprisingly also the sunniest day of the month, see below).

The mean daily maximum temperature in October was 14.4°C, which is 0.2°C below the 30 Year (1976/2005) average. The mean night minimum temperature in the month was 8.1°C, which is 0.1°C above average. It was the coldest October since 2008 only.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 11.9°C, ranging from a maximum of 14.6°C on both 9^th and 10^th to a minimum of 7.6°C on 26^th.

October commenced on a wet note with the wettest day of the month occurring on 2^nd, when 13.4 millimetres of rainfall was recorded. By the end of the month the rainfall total had reached 63.9 millimetres, which is 112% of the 30 Year (1971/2000) average.

The number of "rain days" (0.2 millimetres or more) in October was 16, with rainfall equalling or exceeding 1.0 millimetre on 13 of these days. It was the wettest October in Royston since 2004.

The cumulative total of rainfall for 2010 as at the end of October was 515.5 millimetres, which is 108% of normal.

October registered 6 days without any sunshine at all, this being the highest figure in any month since February. Total sunshine in the month was 112.4 hours, which is 98% of the 1971/2000 average. It was the sunniest October since 2008 only.

The sunniest day of the month was 25^th with 9.1 hours of bright sunshine. This made it the sunniest day in the last week of October in any year since at least 1997.

The mean wind speed in October was 5.8 mph and the maximum wind gust speed recorded was 34 mph on 3^rd. The highest daily (00/00 GMT) mean wind speed in the month was 10.8 mph on 26^th whilst the lowest daily mean wind speed was 1.7 mph on 14^th.

An analysis of wind directions as observed at 0900 GMT daily reveals a fairly even spread through the month, as follows: NORTH 3 days, NE 5, E 1, SE 2, S 6, SW 7, W 3, NW 4 and CALM 0.

The mean MSL air pressure in October was 1012.3 mB, which is 1.4 mB below the 30 Year (1976/2005) average. The highest and lowest air pressure values recorded in October were 1029.0 mB on 25^th and 991.9 mB on 3^rd respectively.

The mean relative humidity in October was 84.3%. The highest daily (00/00 GMT) mean relative humidity was 91.7% on 4^th, and the lowest daily mean relative humidity was 74.8% on 21^st. The absolute lowest relative humidity reading in the month was 49% at 1325 GMT on 10^th and 1415 GMT on 17^th.

Fog (visibility < 1000 metres at 0900GMT) was observed on 3 days (4^th, 8^th and 10^th) in October.

Met. Observer, Royston (Iceni) Weather Station

6th November 2010

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