Royston (Iceni) Weather Station

Daily Weather Observations - October 2006

A very mild October was experienced in Royston, whilst rainfall and sunshine were both a little above average.

Although October was a very mild month it did not quite break the record (back to 1972) since the mean temperature in October 2001 was 0.2°C higher. However, it was only just the second warmest October since at least 1972, the mean temperature exceeding October 2005 by the narrowest of margins, 0.1°C.

The mean daily maximum temperature in October was 17.2°C, which is 2.6°C above the 30 Year (1976/2005) average for Royston, whilst the mean night minimum temperature was 2.9°C above average at 10.9°C. A significant feature of the temperature regime was that the daily maximum temperature exceeded its respective 30 Year (1976/2005) daily mean on every day of the month except one (5^th).

Despite the overall warmth of the month the highest daily maximum temperature of 20.5°C on 9^th was not exceptional, having been exceeded in October in 13 years since 1972. The lowest temperature recorded in October was 7.0°C on 14^th. On this date the lowest grass minimum temperature of the month, 4.5°C, was recorded also. As indicated by these figures the month was completely air and ground frost free.

The lowest daily maximum temperature in October was 14.0°C on both 23^rd and 27^th. This compares very favourably with the 30 Year mean maximum temperature for the month of 14.6°C and illustrates the persistent warmth of the month with an absence of any cold days. The highest night minimum temperature in October was 14.9°C on 10^th.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 14.4°C, the earth temperature ranging from a maximum of 16.7°C on 1^st to a minimum of 12.6°C on 28^th.

The October rainfall was heading for a significantly above average total until a relatively dry last week which restricted the excess to only 10% above the 30 Year (1971/2000) average. Total rainfall was 62.9 millimetres, the number of "rain days" (0.2 millimetres or more) being 16, and the number of days with rainfall exceeding 1.0 millimetre being 12. This was the 3^rd successive October to experience rainfall marginally above the average, the October 2006 total being the lowest since 2003, however.

Rainfall duration in October was 31.3 hours.

Thunder was heard in October on 2 days (1^st and 11^th). Hail was observed to fall on just 1 day (1^st).

Although the October sunshine total of 131.7 hours was 115% of the 1971/200 average it was the sunniest October since 2003 only. The sunniest day of the month was 7^th with 10.0 hours sunshine. Only 2 days (5^th and 22^nd) in October were completely sunless.

The mean wind speed in October was 3.1 mph, the highest daily (00/00GMT) mean wind speed being 8.4 mph on 6^th, and the lowest daily mean wind speed being 0.0 mph (to nearest 1 decimal place) on both 13^th and 14^th. The maximum wind gust speed in the month was 44 mph on 26^th.

Almost two-thirds of the days in October experienced winds with a southerly component as indicated by the following analysis of wind directions at 0900 GMT: NORTH NIL days, NE 1, E 1, SE 5, S 7, SW 8, W 5, NW 2, and CALM 2.

The mean MSL air pressure in the month was 1006.9 mB, which is almost 7 mB below the 1976/2005 average. The highest and lowest air pressure values recorded in October were 1031 mB and 981 mB on 13^th and 24^th respectively.

October was a month of fairly high relative humidity values which are reflected in the mean for the month of 90.2%. The highest daily (00/00 GMT) mean relative humidity value was 98.9% on 11^th whilst the lowest daily mean was 77.2% on 7^th.

The absolute lowest relative humidity reading in October was 42% at 1320 GMT on 7^th.

Fog (visibility < 1000 metres at the 0900 GMT observation hour) was recorded on 3 days (13^th, 14^th and 18^th) in the month. On 13^th visibility fell below the 200 metre threshold at 0900 GMT.

Richard Barker

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

6^th November 2006

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