January was a dull and wet month in Royston, but with temperatures not far from normal.

After the record breaking cold December a mild spell around mid-month lifted the mean temperature for January close to the average for the month. Even so it became the 8^th consecutive colder than average Winter month (from December 2008), albeit by a narrow margin on this occasion.

The mean daily maximum temperature in January was 6.4°C, which is 0.5°C below the 30 Year (1981/2010) average. The mean night minimum temperature was 0.1°C above average at 2.6°C. In consequence it was the mildest January since 2008.

The highest daily maximum temperature recorded in the month was 12.8°C on 13^th, whilst the lowest such daily maximum temperature was 1.5°C on 21^st. As regards night minimum temperatures the highest was 11.1°C on 14^th and the lowest –4.1°C on 29^th. The lowest grass minimum temperature in the month was –7.2°C, also on 29^th.

Totals of 10 air frosts and 16 ground frosts occurred in January. Air frost duration in January was 57.3 hours, compared with 386.5 hours in December 2010.

The mean earth temperature at 30 cms depth as recorded at 0900 GMT daily was 4.8°C, rising to a maximum of 7.0°C on 17^th and falling to a minimum of 3.5°C on 30^th and 31^st.

The snowy regime of December 2010 did not continue into January and the month was surprisingly completely snow free. All precipitation fell as rainfall and the total of 73.5 millimetres was 144% of the 30 Year (1981/2010) average, making it the wettest January since 2004. However, the month ended on a dry note with no rainfall at all on the last 5 days.

The number of "rain days" (0.2 millimetres or more) was 20, with rainfall exceeding 1.0 millimetre on 13 of these days. The wettest day of the month was 17^th with 16.2 millimetres rainfall.

January was a very dull month but the sunshine total to 30^th was boosted by over 20% on 31^st by a very sunny day which registered 7.5 hours sunshine (the sunniest day of the month). The eventual monthly total of 42.7 hours sunshine was only 77% of the 30 Year (1971/2010) average. It was the dullest January in Royston since at least 1997.

A total of 12 days in the month were completely sunless. The 6 day period from 22^nd to 27^th produced an aggregate of only 4 minutes sunshine, whilst the 9 day period from 22^nd to 30^th managed only 1.5 hours sunshine.

The mean wind speed in January was 6.5 mph, and the highest wind gust recorded was 35 mph on both 5^th and 15^th. The highest daily (00/00 GMT) mean wind speed was 14.6 mph on 15^th whilst the lowest daily mean wind speed was 1.9 mph on 30^th.

The analysis of wind directions as observed at 0900 GMT daily was as follows: NORTH 4 days, NE 3, E 2, SE 0, S 5, SW 7, W 7, NW 3, and CALM 0.

The mean MSL air pressure in the month was 1017.5 mB, which is 1.5 mB above the 30 Year (1981/2010) average. The highest and lowest air pressure readings recorded were 1039.7 mB on 21^st and 985.4 mB on 8^th respectively.

The mean relative humidity in January was 89.1%. The highest daily (00/00 GMT) mean relative humidity was 96.7% on 23^rd; the lowest daily mean relative humidity was 77.9% on 28^th. The absolute lowest relative humidity reading in January was 65% at 1515 GMT on 27^th.

Fog (visibility < 1000 metres @ 0900 GMT) was observed on only 1 day (17^th) in January.

Met. Observer, Royston (Iceni) Weather Station

10th February 2011