Marlborough's weather in 2017: warmer and drier than average
In recent decades, hardly a year has gone by when records for the weather in Marlborough have not recently been broken. The year 2017 was no exception at my ‘windrushweather’ station that was started in 1984.
The warming trend observed over recent years continues with the three months of March, May and June being significantly warmer than the previous highs with mean temperatures of +2.2C, +1.9C and +2.0C, respectively.
However, the year did start very cool with the coldest January for seven years and a mean temperature 1C below the 33-year average. We endured 17 air frosts, 11 of which were consecutive and the night of January 21 saw the thermometer drop to -5.9C. This was not a record for windrushweather, as in January 2009 the thermometer fell to a low of -13.1C.
February changed the pattern as although we had three days when snow fell, the month was very warm being 1.5C above the long-term average. This was in spite of the fact that on 14 days the sunshine recorder was not triggered.
Not surprisingly, being the warmest on record, March 2017 gave us 87 hours of strong sunshine, over 11 hours on March 26. It is interesting to note that only four years previously, in March 2013, we endured a record breaking cold month with the mean temperature 3.7C below the 33-year record. It was notable that this was the third consecutive month with below average rainfall.
The trend for drier than average months continued into April as only 8.2mm of rain was recorded when the average was 59.7mm. We enjoyed a warm start to the month with 10 out of the first 12 days producing above average maxima. There were 20 totally dry days.
I have already mentioned that May was the warmest on record. The temperatures soared to 26.2C and 26.3C on two consecutive days towards the end of the month. There were 119 hours of gloriously strong sunshine with nearly 16 hours on May 26.
June gave us a summer month to remember with the mean temperature 2C above the 33-year average and 16 dry days. From June 13 to June 26 temperatures were frequently in the high 20s peaking at 30.8C on June 20 followed by 32.2C on June 21, a record June maxima for this station.
July continued where June left off with a very warm if not hot first half of the month as the thermometer soared again to maxima of 28.6C and 29.9C on July 5 and 6. The hot spell was temporarily broken on July 11 with torrential rain amounting to 26.2m. Summer departed for the second half of the month with 12 wet days out of the final fortnight.
August did not turn out to be the final summer month that was needed for the holidays, as there were only 16 dry days with the mean temperature 0.5C below the long-term average. Thunderstorms occurred on two days.
September was also a disappointing month with the rainfall total 14mm above average and the temperature 0.5C below average. Exceptionally, there were only six totally dry days with fog or mist occurring early morning on nine days.
The opening days of October saw a turnaround in the weather with the driest October on record producing just 31.3mm of rainfall when the 33-year average was 86.4mm. The temperatures were quite the opposite with the mean being a significant 1.4C above the average.
Another record was set as the coldest October day I have recorded occurred on the last but one day of the month with a maximum of just 11C compared to the mean of 14.6C.
November continued the pattern of below average rainfall, being a significant 32mm below the average. It was a cool month with the mean 0.6C below the average as we experienced eight days of air frosts, the lowest of -2.8C occurring on November 25. Although we started the month with temperatures into the teens, the thermometer struggled to reach just 3.3C on November 30.
December brought us the lowest barometric pressure for this month since records began in 1984. There were many days with thick cloud brought to us thanks to the Jet Stream conveyor belt as low-pressure systems regularly crossed the country.
Not surprisingly, the rainfall was 19mm above average. And that was very welcome: due to the previous drier months our local rivers were running very low.
As 16 of the warmest 17 years have occurred globally since 2000, it is not surprising to find that in Marlborough, three months in 2017 set new records for this station as regards higher temperatures.
With a mean temperature of 10.4C, the year 2017 was 0.8C above my 33-year average and the fourth warmest year I have recorded occurred in 2006, 2011 and 2014. The contrasting years occurred in 1986 and 2011 with means of 8.0C and 10.7C respectively.
It was the driest year in Marlborough since 2011 with just 742mm of rainfall set against the 33-year average of 848mm. The record highs and lows for annual rainfall are 594mm in 1996 and 1146mm in 2002.
It is interesting to note that whilst we had 742mm of precipitation during the year, an amount equal to 577mm of moisture evaporated into the atmosphere from the ground, water sources and plant life. That left a low amount of water available to fill our rivers and aquifers.
During the year we enjoyed 1163 hours of strong sunshine, 172 totally dry days, snow on six days, no UV light on 18 days and fog occurring at the time observations are taken (08.00) on 36 days.
More details can be found at my station's website.