Royston (Iceni) Weather Station

Daily Weather Observations - October 2009

It was a dry but dull October in Royston, whilst temperatures were a little above average.

After the very dry September the month of October did not fare much better for rainfall and the monthly total of 31.2 millimetres was only 55% of the 30 Year (1971/2000) average.

The rainfall of 2.0 millimetres on 3^rd October was the first measurable rainfall since 15^th September, and a further indication of how dry the early Autumn has been is that rainfall from 3^rd September to 2^nd October inclusive was only 1.0 millimetre.

The number of "rain days" (0.2 millimetres or more) in October was 14 whilst rainfall exceeded 1.0 millimetre on 10 of these days. The wettest day of the month was 7^th with 6.9 millimetres rainfall. It was the driest October in Royston since 1996. Rainfall duration in the month was 22.4 hours.

The dry conditions in September and October have brought the year to date rainfall total to below average. Total rainfall in 2009 to the end of October amounted to 442.7 millimetres, which is 93% of the 1971/2000 average.

For the 8^th consecutive month the mean temperature in October was above average, this month by a somewhat modest 0.8°C. It was the mildest October since 2006 only.

The mean daily maximum temperature in October was 15.3°C, which is 0.7°C above the 30 Year (1976/2005) average. The mean night minimum temperature was 0.8°C above average at 8.8°C.

The highest daily maximum temperature recorded in the month was 19.3°C on 6^th. The lowest night minimum temperature in October was 3.4°C on 18^th meaning that any air frost was avoided this month. However, 2 ground frosts were registered, on 8^th and 18^th, and the grass minimum temperature of –1.4°C on this latter date was the lowest of the month.

The mean earth temperature at 30 centimetres depth as read at 0900 GMT daily was 12.8°C. The highest and lowest earth temperatures recorded in the month were 15.4°C and 11.1°C on 1^st and 20^th respectively.

For the first month this year the sunshine total was actually below average. Total sunshine in October was 97.0 hours, which is 84% of the 1971/2000 average. However, only 3 days (5^th, 21^st and 26^th) in the month were completely sunless.

The sunniest day of the month was 13^th with 9.2 hours sunshine. It was the dullest October since 1998.

The mean wind speed in October was 5.1 mph, whilst the maximum wind gust speed recorded was 38 mph on 3^rd. The highest daily (00/00 GMT) mean wind speed was 12.8 mph on 3^rd and the lowest daily mean wind speed was 1.4 mph on 13^th.

The analysis of wind directions as observed at 0900 GMT daily was as follows: NORTH 3 days, NE 0, E 2, SE 4, S 8, SW 3, W 9, NW 2 and CALM 0.

The mean MSL air pressure in the month was 1015.6 mB, which is 2 mB above the 30 Year (1976/2005) average. The highest and lowest air pressure values in October were 1033.1 mB and 994.6 mB on 15^th and 21^st respectively.

The mean relative humidity over the whole month was 80.6%. The highest daily (00/00 GMT) mean relative humidity was 91.5% on 21^st, whilst the lowest daily mean relative humidity value was 69.4% on both 1^st and 4^th.

The absolute lowest relative humidity reading in October was 48% at 1430 GMT on 4^th.

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

Met. Observer, Royston (Iceni) Weather Station

8^th November 2009

Boadicea – Queen of the Iceni

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