Royston (Iceni) Weather Station

Daily Weather Observations - October 2003

October 2003 was a dry and very sunny month in Royston, but temperatures were below average.

Night minimum temperatures were below average for virtually the whole of October, whilst day maximum temperatures were above average until around mid-month when they too slipped below average. Overall it was the coldest October in Royston since 1993.

The mean daily maximum temperature in October was 13.9°C, which is 0.4°C below the 30 Year (1973/2002) average. The highest temperature recorded in the month was 19.3°C on 1^st. In contrast, the lowest day maximum temperature was 8.7°C on 22^nd.

The mean night minimum temperature was 5.0°C, which is 2.8°C below the 30 Year average. This is the lowest such value since the notably cold October of 1974 when day maximum temperatures were significantly lower than in October this year. The lowest temperature recorded in the month was 0.2°C on 24^th, thus October just avoiding any air frost. However, ground frost was recorded on as many as 13 nights in the month, this being the highest number of ground frosts in October since records commenced in 1972. The mildest night in the month was 10^th with a minimum temperature of 13.0°C.

The earth temperature at 30 cms depth as observed at 0900 GMT daily fell steadily through the month, from a peak of 14.0°C on 4^th to a minimum of 7.0°C on 28^th. The mean earth temperature in October was 10.4°C.

This year has been exceptionally sunny in Royston and October followed this trend to an even greater degree! Sunshine for the year to the end of October stood at 1828.7 hours which is 337.9 hours higher than the average for the whole year. The long term annual sunshine average was actually passed on 8^th September.

As regards the October only sunshine this was quite exceptional at 167.2 hours, which is 154% of average. No fewer than 9 days in October exceeded 9 hours sunshine, the highest daily total of 9.8 hours being recorded on 11^th. Only 1 day (31^st) in the month was completely sunless, although 2^nd came extremely close with only half a minute of sunshine! Over England & Wales as a whole it was the sunniest October since 1961 (when the present sunshine series began), and possibly a lot longer.

The very dry spell which began on 2^nd August (in an already dry year) continued for the first 3 weeks of October, during which only 5.4 millimetres of rainfall was measured. The rest of the month was somewhat wetter but the only significant amount of rainfall recorded was 13.5 millimetres on 30^th. This amount helped increase the total for the month to 34.1 millimetres, which is 60% of the 1971/2000 average for Royston. It was the driest October since 1996.

The number of "rain days" (0.2 millimetres or more) in October was 15, whilst on 7 of these days rainfall exceeded 1.0 millimetre. Rainfall duration in the month was 48.8 hours. Rainfall for 2003 to the end of October was 340.3 millimetres, which is 71% of normal and represents a deficiency of 136.9 millimetres over the 10 months.

Hail was observed to fall on 2 days (4^th and 23^rd) in October.

The mean wind speed in October was 2.8 mph. The highest daily (00/00 GMT) mean wind speed in the month was 9.7 mph on 6^th, whilst the lowest daily mean wind speed was 0.1 mph on 2^nd. The highest wind gust speed recorded in October was 39 mph on 8^th.

The analysis of wind direction as observed daily at 0900 GMT shows north-east and west as the dominant directions, as follows:- NORTH 0 days, NE 13, E 0, SE 0, S 1, SW 4, W 10, NW 2 and CALM 1.

The mean MSL air pressure in October was 1014.2 mB, which is very close to the average of the last 30 years. The highest and lowest air pressure values recorded in the month were 1033 mB and 971 mB on 18^th and 31^st respectively.

The mean relative humidity in October was 81.5%. The highest daily (00/00 GMT) mean relative humidity was 98.1% on 31^st compared with the lowest such daily mean of 67.3% on 5^th. The absolute lowest relative humidity reading in the month was 35% at 1355 GMT on 5^th.

Fog (visibility < 1000 metres) was observed at the 0900 GMT observation hour on just one day (18^th) in October.

Richard Barker

Richard Barker

Met. Observer, Royston (Iceni) Weather Station

5^th November 2003

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