A warm year, night-times especially; a little wetter than average but lacking in sunshine.
January felt a very dull month, but in fact total sunshine was above average and every day received some bright sunshine. It was the six days from the 16th to the 21st which felt most dark and dreary as we experienced a persistent easterly air stream in Durham. It was not as mild as January 2016; nevertheless mean air temperature was above average, equal 60th highest in 168 years. The mean maximum was equal 48th highest since 1900 and the mean minimum was equal 37th warmest since 1900. It was the driest January since January 2012 (when the first three dry month were followed by record-breaking rainfall totals) and overall the 60th driest January on record since 1850. The 12-month rainfall total was now negative for the first time since November 2015.
February experienced well above average temperatures, at night in particular. The mean air temperature was just below last year’s, equal 60th warmest since 1850. The mean maximum was equal 27th warmest since 1900 and the mean minimum was 4th equal highest since 1900. Rainfall was well above average for February, the 14th wettest since 1850. Not surprisingly, sunshine hours were just a little below average for February therefore.
March was exceptionally mild. It was the 7th equal warmest on record since 1850 and the warmest since 2012. The mean maximum was the equal 11th warmest since 1900, although still 2.5°C cooler than the remarkable March 2012. The mean minimum was the 3rd highest since 1900, only exceeded in 1957 and 1938. Minima of 11.9°C and 10.5°C on the 30th and 31st respectively certainly helped to achieve the very high average minimum temperature. Twelve days had maximum temperatures lower than 10.5°C and 18 days were cooler than 11.9°C! There were only 7 ground frosts, the lowest March total since 1999. March 2017 is one of ten to have had as few as three air frosts; only three years have had only two air frosts in March: 1938, 1991 and 1999. The 25th was the warmest March day in Durham (16.5°C) since a remarkable run of 6 days at the end of 2012 were 18.7°C or warmer including the record-breaker 21.8°C (28/3/12). Rainfall was just below average and sunshine just above.
April was the 20th equal warmest since 1850; eight of the even warmer Aprils have been since 2000. It had the 20th equal highest mean maximum and the 17th equal highest mean minimum temperature. There was the warmest April day (9th: 19.7°C) since the exceptional April 2011 when four days exceeded 20°C. As widely publicised, April was a dry month, with less than two-thirds of average total at Durham. As expected, it was a sunny month, the 29th sunniest April in Durham since 1881.
May had the highest mean minimum on record since 1850 (8.0°C), well ahead of 2003 and 2014 (7.7°C). The mean maximum was the 14th equal highest on record since 1850. It is no surprise therefore that the May mean air temperature was 2nd warmest on record since 1850, exceeded only in 1952. The absolute minimum on 26th (14.1°C) was the 3rd equal highest for any May night at Durham since 1850, beaten only in 1858 and possibly 2004 (but this value is open to some doubt). The minimum of 13.8°C on 24th was the 6th highest ever May value. Altogether there were 7 occasions when the absolute minimum was above 10°C, mainly towards the end of the month; this total has only been exceeded in 1953 (9). There were 6 straight days with maxima above 20°C but this May total is by no means a record, only the 16th equal highest total since 1850; there were 11 days with maxima above 20°C in 1918 and 1952. This was the equal 16th driest May since 1850, equal to 2005, and the driest since 2001. It was the 3rd warmest spring on record since 1850 (9.5°C), exceeded only in 2004 and 2011; it was the 27th driest spring, reflecting the dry, warm conditions generally across the country.
June was the 7th equal warmest at Durham since 1850. Whilst the mean maximum temperature was only modestly above average (but still the 40th highest since 1900), the mean minimum air temperature was the highest on record for June. The absolute minimum on the night of 17th was the highest June minimum since 1997 (equalled in 2006). There were three very warm June days in the middle of the month with 27.3°C on 18th being the 36th hottest June day since 1850 (n=5040). There was almost double the average rainfall for June, the wettest June since 2012 and overall the 9th wettest June since 1850. Sunshine was well below average, not quite as bad as last year, but still the 15th equal lowest total for June since 1882. No doubt the amount of cloud cover influenced the high night-time temperatures noted above.
Mean air temperature in July was exactly average, barely warmer than June, but only the coolest July since 2015. Daytime temperatures were disappointing but night-time temperatures above average. The 12-month average mean air temperature had reached 10°C in June but fell back to 9.95°C in July, but still one of the highest values on record: 35th highest in exactly 2000 averages. July was another wet month, but not exceptionally so. All long-period rainfall totals were now slightly above average again. Not unexpectedly, sunshine was below average, the lowest July total since the wet summer of 2012. Curiously, March, April and May were all sunnier than June and July!
August was the first month since November 2016 to have below-average mean air temperature. Daytime maximum temperatures were disappointing but night-time minima were again above average. Rainfall was below average although measurable rain fell on half the days. In terms of bright sunshine, it was another disappointing month, the 18th lowest August total since 1882.
Overall, summer was only marginally cooler than last year, but still ranking equal 38th highest in 168 years. Only above-average minima kept the overall mean air temperature at this relatively tolerable level. It was a wet summer, with the 135th highest total in 168 years. Summer sunshine was in short supply: the 3rd lowest total on record. Using the Davis (1968) index of summer weather (which is based on mean air temperature, total rainfall and hours of sunshine), this was the 24th worst summer since 1900 (equal with 2015), not nearly as bad as 2012 but reflecting a general deterioration in Durham summers since the mid-1990s.
For the second month in a row, mean air temperature in September was just below average; like August, daytime temperatures were disappointing but night-time minima were above average. Rainfall was well above average, the wettest September since 2012 and 31st wettest since 1850. Whilst the wettest “day” was technically the 12th (15.4mm), the combined total for the evening of the 12th and morning of the 13th was 28mm. It was the 11th dullest September on record, and the worst since 2001.
The mean maximum temperature was the highest for October since 2005 and 12th highest since 1900. The mean minimum temperature equalled the value in 2005, these being the joint 2nd highest on record, only beaten in 2001. Mean air temperature was the equal 6th highest for October on record (with 1995). Warmer Octobers include the recent years 2001 (warmest), 2005 and 2006, but also 1921 and 1969. There was only one ground frost and no air frost. October averages five ground frosts but the last five years have seen only one ground frost in four of the years and two in the other. October was a dry month, the driest October since 2007 and the 23rd driest since 1850. Despite the lack of rainfall, it was not a sunny month, but nothing so poor as 1897 when there were only 29 hours of bright sunshine in October. It was cloudy enough to keep minimum temperatures above freezing and there were 13 rain days despite the low total rainfall.
November was warmer than average, but not exceptionally so. All three “mean” measures of air temperature were above average. Even so, the number of ground frosts (17) was also above average. It would have been a dry month too, except for the exceptional downpour on 22nd when a total of 38.2mm was recorded, the equal 58th wettest day on record at Durham since 1850. If we use the “meteorological day” (starting 0900), then the total was 39.2mm, equal to the total on 28th July 2013, the 50th equal wettest day on record and thereby the equal wettest day since 16th April 2005. There were some exceptional hourly intensities: 9.4mm in the hour ending 2000 GMT; 9.2mm in the hour ending 2200 GMT and 7.2mm in the hour ending 2300 GMT. The number of rain days (12) was well below average (18). It was a sunny month, the sunniest November since 2013 and the 7th sunniest November at Durham since 1882.
December was above average temperature but not greatly so, the equal 68th warmest December since 1850. It was both sunny and dry. This was the 37th driest December on record, drier than last year but wetter than 2014; and all three quite unlike the very wet December 2015. This was the 6th sunniest December since 1882 but only the sunniest since 2014 (which is the sunniest December on record: 96 hours).
2017 was the 10th warmest year on record at Durham since 1850, only marginally cooler than 1990 which had a memorably warm summer. The mean maximum air temperature was the 20th warmest on record (since 1900) and the mean minimum air temperature was the 3rd warmest on record, beaten only by 2004 and 2014. The overall warmth of 2017 was therefore more due to warm nights than warm days. Even so, there were 82 ground frosts, a higher number than in the previous three years, although still the 11th lowest total on record (since 1954). Rainfall was just a little above average but not greatly so, only the 70th wettest in 168 years. Total sunshine hours were again below average, the 29th lowest annual total since 1882. Sunshine has not exceeded the average at Durham since 2011. This deserves some further attention since this may not reflect regional climate change but rather a local site effect with tree growth possibly shading solar radiometer at low sun angles.
|Mean air temperature||3.8||5.7||7.7||8.5||12.3||14.8||14.9||14.6||12.6||11.8||6.0||4.2||9.7|
|Difference from average||0.8||2.5||2.7||1.5||2.4||1.8||0.0||-0.1||-0.1||2.0||0.3||0.3||1.2|
|Mean maximum temperature||6.3||8.1||11.2||12.9||16.6||18.4||18.8||18.6||16.1||14.7||9||6.9||13.1|
|Mean minimum temperature||1.2||3.2||4.2||4.1||8.0||11.2||10.9||10.6||9.0||8.9||3.1||1.5||6.3|
|Absolute maximum temperature||11.4||13.5||16.5||19.7||25.3||27.3||23.8||21.8||18.9||19.2||14.1||12.4||27.3|
|Absolute minimum temperature||-3.1||-1||-0.5||-0.8||1.8||7.8||8.2||6.1||4.1||1.6||-1||-6.7||-6.7|
|Number of ground frosts||19||9||7||8||1||0||0||0||0||1||17||20||82|
|Difference from average||-17.1||39.8||-8.8||-18.3||-32.4||51.6||19.6||-17.1||31.8||-22.0||14.0||-23.5||18.5|
|Highest daily rainfall||13.2||18.2||10.6||7||6.4||25.8||13.2||18.4||15.4||8.6||38.2||8||38.2|
|Number of rain days||10||19||11||9||9||12||16||15||20||13||12||20||166|
|Maximum daily sunshine||7||5.8||11||11.2||11.3||14.3||10.9||9.4||6.9||7.3||6.6||6.6||14.3|
Professor Tim Burt
Department of Geography