The Weather at Durham in 2015

Overall, a warm, wet year but with a disappointing summer.

Although January felt wintry, especially at the end of the month, it was in fact well above average temperature, helped by some very mild days in the first half of the month. It was cooler than January 2014 but still equal 37th warmest in 167 years. With a maximum of 13.3°C, it was the warmest New Year’s Days on record (since 1850), the previous record being 12.8°C in 1851. It was a dry month with a maximum daily total of only 9mm. Most significantly, this was the sunniest January at Durham since records began in 1882, beating the previous record holder 2007 by 3 hours. Interestingly, five of the sunniest Januaries at Durham have been this century. Mean air temperature was also well above average in February, but it was still only the 68th equal warmest on record. There were more ground frosts than in 2014 but this is still the 2nd lowest total for February since 1961. It was a dry month, the 20th equal lowest total on record for February since 1850. Sunshine hours were well again above average, with nearly one extra hour per day. Although not as sunny as February 2014, it was still the 28th sunniest February on record since 1882. Overall, it was, nor surprisingly, a mild winter, 29th equal warmest since 1850, so well into the upper quartile. It was also a dry winter, 26th driest on record, the driest since 2006. Most notably, it was the sunniest winter on record at Durham since 1882-3, beating the previous record from 2000. Of the ten sunniest winters, six have been this century.

March was only a little above average temperature and perhaps a little disappointing later in the month as we awaited better spring weather. There were no days above 10°C after the 10th. Both mean maximum and mean minimum were above average, the latter only just so. There was a relatively high number of ground frosts. Rainfall was just below. There were slightly more hours of bright sunshine than usual but all in all this was very much an “average” March. April was a warm month, although not exceptionally so. It was the 19th equal warmest April at Durham since 1850, but nearly a degree cooler than April 2014 (equal 7th warmest). Maximum temperatures were well above average but minima were only just above average. It was another dry month, the 37th driest since 1850. It was the 23rd driest February to April period on record. Not surprisingly, it was a sunny month, the 10th sunniest April since 1882. May was disappointing, the mean air temperature being exactly average, but it was only the coolest May since 2010. There was the lowest mean maximum since 1996, the 35th equal lowest since 1900. The mean minimum was above average. Rainfall was a little above average but all long-term totals remained below average. There was one spectacular downpour on the afternoon of the 19th; only 4.6mm was recorded (hour ending 1500 BST) but it fell in no more than 15 minutes, so the intensity was spectacular: Durham was awash and your correspondent soaked! The amount of sunshine was disappointing, less than in April.

June was the first month with below-average temperature since the previous August, equal 43rd lowest on record since 1850, but only the lowest since 2012. The mean maximum was equal 37th lowest since 1900 while the mean minimum was equal 30th lowest (rather different to the 5th highest in 2014). The warmest day of the month was the last, the best June day since 2011. It was a dry month, the 56th driest June since 1850. Several days received a total of at least six millimetres but none received seven! There was a disappointing amount of bright sunshine, less than in both April and May, but still almost twice the total in 2012, and an hour a day more than in 2014. July was a disappointing month, the second month in a row with below-average temperatures. And it had started so well, with a maximum over 30°C on the 1st.  This was the warmest July day in Durham since 2006 and one of the very few ever to exceed 30°C at Durham. Since 1st January 1850, only 30 days have reached a maximum of 30°C; 1st July 2015 was the 21st warmest day on record at Durham (equal to 15th August 1893). The warmest day on record is 16th July 1876: 33.6°C. All that said, mean air temperature in July was the lowest since 2000, the 44th equal lowest since 1850, only just above the lowest quartile. The mean maximum was the lowest since 2012 and the mean minimum the lowest since 2011. The 12-month mean air temperature was now down to 9.3°C having been just above 10°C in January. Rainfall was well above average but again it was only the worst July since the very poor summer of 2012. Even with an extra day, there were fewer hours of bright sunshine in July than in June. Since 1882, there have been 54 years when July was less sunny than June (n = 134). August was another disappointing month. Night-time temperatures were well above average but daytime- temperatures below average. The mean maximum was equal 51st lowest since 1900 (n=116), but the mean minimum was equal 95th highest. Overall, the mean air temperature was equal 108th highest(n=166), just slightly above average. Rainfall was just above average, with almost half the days recording at least 0.25mm. There was only 81% of the average number of hours of bright sunshine, sadly only just over half the record-breaking total in 1995. For the summer as a whole, it was the coldest summer (13.9°C) since 1987 (equal to 1993). It was the 110th wettest summer in 166 years (203.6mm) and, perhaps most telling of all, there was the 17th lowest amount of bright sunshine (386.1 hours) since 1882. A combined index of summer weather shows this to be the 32nd worst summer at Durham since 1882: roughly a quarter have been worse than 2015 but three quarters were better!

In terms of temperature, September was also disappointing. It was the coolest September since 1994 and ranks equal 117th in 166 years of record. The 12-month running mean was by now the lowest (9.16°C) since December 2013. It was a dry month, although not unusually so, but the amount of sunshine was below average too. October was above average for mean air temperature, because of warmer days; night-time minima were just below average. There were two ground frosts but no air frosts. Apart from the first two days, October was a very dull month. It was the 15th least sunny October since 1882, but only the lowest October total since 2013. There were ten days with less than half an hour’s bright sunshine. Not surprisingly, rainfall was above average for the month, with a notable total of 24.8mm on the 7th. In contrast to much that had gone before, this was the third warmest November on record at Durham since 1850 (mean air temperature: 8.3°C), exceeded only by 2011 (8.6°C) and 1994 (8.4°C). The mean maximum was equal 4th highest on record and the mean minimum was the 2nd highest on record (both since 1900). The absolute maximum of 17.5°C on 1st November was the 3rd warmest November day on record since 1850, beaten only by 2/11/1927 and 4/11/1946 – both with a maximum of 18.9°C. Remarkably, 18 days had a maximum over 10°C; there were two minima over 10°C too, 14.2°C on the 10th being particularly notable for November. This was one of only eleven Novembers with just two air frosts, but 5 have had just one and 6 no air frosts at all. Of the 22 Novembers with 2 air frosts or less, seven have been from 2000 onwards. It was the 21st wettest November since 1850, but five Novembers from 2000 onwards have been wetter. As befits a wet month, it was the 35th least sunny November since 1882, the lowest total since 2002.

December was easily the warmest on record at Durham since 1850 (7.8°C), beating the previous record of 7.3°C in 1988. It was the warmest maximum (0.2°C above the 1988 value); a mean maximum of 10.3°C is more like early April or late October! Likewise, it was the highest mean minimum, a huge 0.7°C above the 1934 mean. There was the equal highest (with 1988) number (20) of December days with a maximum over 10°C. More remarkable was the number of minima over 10°C: since 1900 there had been a total of only13 December nights with minima over 10°C but December 2015 added 4 to that total; only 1974 had had more than 1 (2)! There was a very low number of ground frosts (7), the third equal lowest total since 1954 and the lowest since 2002. It was the wettest December since 1978, the 8th highest December total since 1850. The combined total for Christmas Day and Boxing Day was 45.4mm, with 26.6 recorded on Christmas Day itself, the wettest day of the year and indeed the wettest Christmas Day in Durham since records began. All long-period rainfall totals are now well above average, given three wet months at the end of the year. Whilst the amount of sunshine was almost average, there were 10 days with no sunshine recorded at all, but this is not an unusual total for the winter months.

For the year as a whole, three months fell below the 1961-1990 average temperature (June, July, September) so, despite a warm end to the year, the overall average (9.3°C) was well down on last year. Whilst well above the 1961-1990 average, it is only just above the average for the last 30 years. 2015 was the 37th wettest year on record at Durham, a dry first half to the year and a wet second half. Five of the last ten years have been wetter. Sunshine hours were once again below average, for the fourth year in a row. There was, like 2014, a low number of ground frosts (72) and, despite the high rainfall total, a relatively low number of rain days (167). This reflects the tendency for mean rainfall intensity gradually to have increased since the 1890s and particularly since the 1960s (Burt et al., 2015).

Reference

T.P. Burt, J. Boardman, I.D.L. Foster and N.J.K. Howden. (2015). More rain, less soil: long-term changes in rainfall intensity with climate change. Earth Surface Processes and Landforms. DOI: 10.1002/esp.3868.

Professor Tim Burt
Department of Geography
Durham University