Marlborough's April weather: not perhaps the cruellest month, but nearly the driest

Written by Eric Gilbert on .

Taking advantage of some pre-frost blossom... (Photo: Eric Gilbert)Taking advantage of some pre-frost blossom... (Photo: Eric Gilbert)The outstanding feature of April was the lack of any serious precipitation.  The total to fall on Marlborough was just 8.2mm from the few light rain showers and from the wet snow that fell during the late afternoon of the April 25.

The record for the driest April in Marlborough was in 1984 - when this station started recording - with just 2.0mm, followed by 5.4mm in 2011 and 6.7mm in 2007.

There were 20 dry days in April 2017 with the wettest day being April 25 - producing 2.2mm and another 2.1mm on April 30.

There just 4 ‘wet’ days in the whole month - that's days which the Meteorological Office class as having precipitation equal to or above 1mm.

The 33-year average for April was 59.7mm making a deficit of 51mm for April. When an overview of the past few months is analysed the situation is even more severe. The winter months of December to February produced a deficit of 99mm and March was 9mm below the long-term average.

The precipitation over the past five months was 159mm below the 33-year average or over 6 inches in old money. The slight falls this last month, in both the River Og and River Kennet levels, can be traced not only to the lack of rainfall, but also to the fact that in April 69mm of equivalent rainfall evaporated into the atmosphere from ground sources and plant life.

There is a contrast when analysing the temperatures over the past month comparing day and night. The daytime average was +1.5C but the cold nights meant the average was -0.9C. This gives a mean of +0.3C for the complete month.

Looking back over the years the coldest April occurred in 1986 being 2.9C below the average and the warmest in 2011, which was 3.7C above the average.

There were seven air frosts.  The most severe occurred at the end of the month during the night of the April 26/27, when the thermometer fell below zero for eight hours giving a minimum of -3.0C at dawn. This resulted in much damage to new growth and existing spring flowers - sadly this damage included my rhododendrons and apple blossom.

There were several windy days towards the end of the month with gusts to 30mph on April 30.

We enjoyed 150 hours of strong sunshine with the solar energy four per cent above the seven-year average.

The dry weather with cold nights was mainly due to the consistent high pressure and winds predominantly from a northerly quarter. The barometric pressure for April was a significant 7mb above the long-term average at 1023mb.

This 1649 quotation from Ralph Josselin, a Puritan minister, diarist and weather-watcher from Essex, might very well be applicable to the past month with its dry weather and frosty nights: “Dry, windie, indifferently cleare in the nights very cold, and much given to frosts … good to purge the aire, and to prevent infection. Oh Lord watch over me and mine”.