After the cold Winter followed by only an average mean temperature in March, the month of April in Royston was warm, dry and sunny.

Spring is traditionally the driest season of the year in Royston but so far this year Spring has been even drier than the average.

The dry March has been followed by a very dry April and rainfall in April totalled only 17.3 millimetres, which is only 39% of the 30 Year (1971/2000) average. However, it was the driest April since 2005 only. In the 16 day period from 8^th to 23^rd inclusive no measurable rainfall at all was recorded and the wettest day of the month, 25^th, yielded only 4.0 millmetres rainfall.

The number of "rain days" (0.2 millimetres or more) in April was 9, and on 6 of these days rainfall exceeded 1.0 millimetre. Hail was observed to fall on just 1 day (4^th) in the month but no thunder was heard on any day in April. Rainfall on 1^st May was 19.4 millimetres, exceeding the whole of the April total!

Rainfall for 2010 to the end of April was 148.7 millimetres, which is 86% of average.

April was a warmer than average month, particularly by day, whilst night temperatures were near normal. The mean daily maximum temperature in April was 15.6°C, which is 2.5°C above the 30 Year (1976/2005) average. The mean night minimum temperature was 0.1°C above average at 4.6°C. April this year was not quite as warm as last year but was warmer than in 2008 so no records were broken in this respect.

The highest temperature recorded in April was 21.5°C on 28^th, a value which has been exceeded in April in 12 of the previous 37 years. The lowest temperature of the month was 0.5°C on 22^nd ; the lowest grass minimum temperature of –3.6°C occurred on this date also.

As indicated, no air frosts occurred in April but 12 ground frosts were recorded. This was the highest number of ground frosts in April since 1996.

A 7 day spell in April from 17^th to 23^rd inclusive in which 71.3 hours sunshine was accumulated was largely responsible for the monthly sunshine of 172.7 hours exceeding the 30 Year (1971/2000) average by 18%.

The sunniest day of the month was 23^rd with 12.8 hours sunshine. Only 1 day (7^th) in the month was completely sunless. Despite the excess of sunshine this April’s total fell short of April last year by 23.5 hours.

April was a fairly calm month as indicated by a maximum wind gust speed of only 32 mph (on 2^nd), this being consistent with the trend so far this year. The mean wind speed in April was 5.7 mph, also similar to mean speeds registered in the first 3 months of the year.

The highest daily (00/00 GMT) mean wind speed in April was 10.7 mph on 1^st, whilst the lowest daily mean wind speed was 2.1 mph on 9^th.

The analysis of wind directions as observed daily at 0900 GMT shows a fairly even distribution through the month, as follows: NORTH 4 days, NE 6, E 1, SE 2, S 6, SW 3, W 5, NW 3 and CALM 0.

The mean MSL air pressure in April was 1018.9 mB, which is 4 mB above the 30 Year (1976/2005) average. The highest and lowest air pressure values recorded in April were 1034.5 mB and 998.5 mB on 10^th and 2^nd respectively

Fog (visibility < 1000 metres at the 0900 GMT observation hour) was not observed on any day in April.

Met. Observer, Royston (Iceni) Weather Station

6th May 2010