April in Marlborough: not so much cruel as just wet - but with a record breaking warm dayThe variability of our weather always seems to provoke conversation. And when it comes to variability April 2018 was no exception. It even included another broken record - not for rainfall but for temperature.
In Marlborough the month began with a downpour - bringing us the wettest day of the month. Rainfall of 18.2mm on April 1 made it the wettest day since December 26. And with only 13 dry days - against the average for April of 16 - it was not surprising to find that the total rainfall for the month was 4.6mm above the 34-year average at 62.8mm.
Although both January and February produced rainfall a little below average, the exceptional March and then the wetter April totals meant that during the first four months of 2018 the rainfall total was 50mm above the 34-year average.
I have mentioned the variability in our weather and the month provides a clear example: in April 1984 the rainfall was negligible at just 2.0mm, whereas in April 2000 we were swamped under 165.2mm.
Reviewing the temperatures throughout April 2018, I find that there was a variation of almost 20C between the warmest and coolest day. The very wet day on April 1 meant that the thermometer struggled to reach 7.3C, whereas under the influence of the very warm air from the Iberian Peninsula on April 19 it soared to 26.5C.
This high beat the previous record set on 23 April 2011 of 26.2C. The April average maximum is 14.01C.
Due to the many cloudy days and occasional warmer spells the mean temperature for April was 1.3C above the 34-year average. This was principally due to the lack of frost and warmer nights under the blanket of cloud that stopped warmth radiating into the atmosphere.
Since my records began, this was only the second year that April did not produce an air frost. The previous one was April 2011 and looking back over the records many an April in the 1980’s and 1990’s produced 9 or 10 days with an air frost.
If you think April was a dull month with occasional brighter periods you were correct. The sunshine total was just 110 hours. I have only had this instrument installed for four years but this total was 60 hours below the three-year average.
This lack of sunshine resulted in the solar energy being only 7 per cent of the ten-year average.
With a sunny start to May and the barometer rising, we look forward to a warmer and drier month.
There's more information on my weather station website.