April 2015 summary

After a damp and breezy start, April was dominated by two periods of high pressure resulting in a lot of settled and dry weather – the rainfall total was 16.4mm, our second driest April on record and our third driest month overall. The wettest day of the month was the 25th, the day when high pressure finally departed, but the total for that day was just 4.4mm.

It was a quiet month too: after a gust of 29kts on the 2nd, winds fell light as high pressure established itself on the 5th. There followed a good deal of warm sunshine once morning mists had cleared, although nights were chilly under clear skies.

The high pressure system moved away on the 11th, allowing a cold front from a low to the north of Scotland to deposit 1.8mm of rain. However, another high became established over the following days bringing a return to settled weather and sunshine. The 15th was an exception – while the rest of southern England basked in sunshine, a sea mist filled the Somerset Levels and the best we could manage was 12.6C. We got our turn the following day, though, with the thermometer reaching 21.2C on the 16th – our second-highest reading for April. A cool easterly airflow brought the lowest temperature of the month, 1.7C, only a few days later, but there were no air frosts. Between 4th and 24 April we recorded less than 3mm of rain.

The high pressure moved off again on the 24th and Atlantic lows took over. Although the airflow was south-westerly, it was polar air drawn down by lows the north of Scotland – hence temperatures dropped, making it feel particularly cold after all the sunshine. The last week of April brought 10mm or rain.

The average temperature for April was a little above normal at 10.1C – the last week took the edge off temperatures after the warm spell in the middle of the month. The average pressure for the month was 1021.4hPa and the maximum was 1038.0hPa, both new April highs for this station reflecting the two spells of anticyclonic weather.