WARMEST SEPTEMBER FOR 10 YEARS AND DULLEST SINCE 2008; SLIGHTLY DRIER THAN AVERAGE

Armagh Observatory, 3rd October 2016. Armagh Observatory reports that September 2016 was much warmer than average, with a mean monthly temperature 1.5 C higher than the most recent (1981-2010) 30-year average September temperature at Armagh. It was also duller than average, with just 91.1 hours of strong sunshine. This is just 80% of the most recent (1981-2010) 30-year average number of hours of strong September sunshine at Armagh and the dullest September for eight years.

This month, with a mean temperature of 14.8 C, was the warmest September at Armagh since 2006, and the third warmest September on record at Armagh, shared with 1846, that is, since daily measurements of air temperature began at Armagh in December 1794. The four warmest Septembers at Armagh are now 15.4 C (1865), 15.0 C (2006) and 14.8 C (both 1846 and 2016).

The warmest day (highest maximum air temperature) was 23.1 C, which occurred on the 5th; and the second warmest day was 23.0 C on the 6th. These warm days were each followed by exceptionally warm nights, producing the two highest minimum daily temperatures for the month, namely 18.0 C on the night of the 5th/6th and 17.0 C on the night of the 6th/7th. These two nights are now the second and sixth-warmest minimum September air temperatures recorded at Armagh since records of maximum and minimum air temperatures began at Armagh in August 1843.

The coldest day (lowest maximum air temperature) was 14.6 C, which occurred on the 30th. The coldest night (lowest minimum air temperature) was 5.4 C on the 22nd. There was one ground frost, also on the 22nd, with a minimum grass temperature of -1.6 C.

September 2016, along with both June and July earlier in the year, was significantly duller than average. It is possible that the relative lack of strong sunshine over the past several months has contributed to the notably damp ground conditions experienced by gardeners and farmers during this summer and early autumn, despite total precipitation during the period being roughly average. This was the dullest September at Armagh for eight years, that is, since September 2008. The sunniest day was the 25th, with 9.0 hours of strong sunshine.

Total precipitation during September was 65.65 mm (2.85 inches), including five trace values, which is approximately 95% of the most recent (1981-2010) average precipitation at Armagh. The wettest day was the 3rd, with 14.2 mm (0.56 inches) of rainfall. Despite the slightly lower than average rainfall, this was the wettest September for four years, that is since 2012. There was measurable precipitation on 21 of the 30 days of the month.

Gulls were seen on several days, notably the 2nd, 5th and 6th; and a low buzzard on the 23rd and 26th. Thunder and lightning were noted on the 3rd, and sheet lightning on the 7th.

These data refer to observations at Armagh Observatory, which has been recording the weather at Armagh since 1795.

For further information, please contact: Professor Mark E. Bailey, Armagh Observatory and Planetarium, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; meb@arm.ac.uk; URL: http://climate.arm.ac.uk/.

Last Revised: 2016 October 6th