Royston (Iceni) Weather Station

Daily Weather Observations - January 2008

It was a sunny and exceptionally mild January in Royston, with rainfall a little above average.

For the second consecutive year January has experienced record breaking warmth. As in January 2007 the mean temperature this January was 3.0°C above average and this makes the month the equal mildest January since at least 1972, when records began at Royston (Iceni) Weather Station.

Also, the absolute maximum temperature in January of 14.1°C on 20^th has been exceeded in only 1 January (1999) since 1972, and then only by 0.1°C. It was the first air frost free January since 1990; since 1972 in only 1 other January (1975) has no air frost been recorded. The number of ground frosts, 6, in the month was the equal lowest (with 4 other years) since 1972.

The mean daily maximum temperature in January was 9.7°C, which is 3.1°C above the 30 Year (1976/2005) average. The mean night minimum temperature was 2.9°C above average at 5.0°C.

The lowest temperature recorded in January was 0.3°C on 28^th; in contrast on both 19^th and 20^th the night minimum temperature was as high as 12.1°C. The lowest grass minimum temperature in the month was -2.2°C on 28^th. The lowest day maximum temperature was 3.9°C on 3^rd.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 6.5°C. The highest and lowest earth temperature values were 8.4°C and 5.3°C on 21^st and 8^th respectively.

Rainfall in January was similar to January last year and the total rainfall of 58.6 millimetres was 114% of the 30 Year (1971/2000) average. The number of "rain days" (0.2 millimetres or more) was 19, with rainfall exceeding 1.0 millimetre on 12 of these days.

The wettest day of the month was 11^th with 13.3 millimetres rainfall. January was virtually snow free with only the slightest fall being noted on 3^rd, this event being restricted to a few small flakes of snow only in the late morning. Rainfall duration in January was 64.6 hours.

Although January experienced dull periods from 1^st/4^th (1.1 hours sunshine) and 17^th/21^st (1.1 hours sunshine) overall it was a sunny month with the total sunshine of 75.9 hours being 37% above the 30 Year (1971/2000 average). This total was 2.3 hours less than in January last year, but 14.1 hours above the sunshine total in January 2006.

The sunniest day of January was 27^th with 7.1 hours sunshine. The number of completely sunless days in January was 6.

January was a generally windy month with the last day of the month being the windiest of all with a mean wind speed of 15.6 mph. A wind gust of 60 mph occurred on this day. However, this was not the strongest wind gust of the month as this occurred on 17^th.

Quite unexpectedly during a shower on 17^th an isolated wind gust of 76 mph occurred at 1525 GMT. This brief phenomenon created a great roar at Royston (Iceni) Weather Station, and a medium sized tree was felled in Newmarket Road, Royston. This was the highest wind gust speed recorded since at least January 1998.

The calmest day in January was 1^st (00/00 GMT) with a mean wind speed of 2.4 mph.

No less than 22 days in the month contained a westerly component in the wind direction at 0900 GMT as illustrated by the following table of daily wind directions at this hour: NORTH 0 days, NE 0, E 2, SE 1, S 6, SW 12, W 10, NW 0 and CALM 0.

The mean MSL air pressure in January was 1008.7 mB, which is 7 mB below the 30 Year (1976/2005) average. The highest and lowest air pressure values recorded in January were 1033 mB and 971 mB on 25^th (and 28^th), and 15^th respectively.

The mean relative humidity in January was 90.4% with a daily (00/00 GMT) highest mean value of 99.5% on 4^th and a lowest daily mean value of 77.1% on 24^th. The absolute lowest relative humidity reading in January was 50% at 1505 GMT on 24^th.

The number of days with fog (visibility < 1000 metres) at the 0900 GMT observation hour in January was 2, 1^st and 28^th, whilst on the latter date visibility fell below the 200 metres threshold.

Met. Observer, Royston (Iceni) Weather Station

6^th February 2008

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