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Armagh Observatory points to climate change as it reports 2023 as warmest year on record

Armagh Observatory

Armagh Observatory has reported 2023 as the warmest year on record.

December 2023 was much warmer than average, wetter than average, and slightly duller than average.

The calendar year 2023 was the warmest year on record at Armagh, but much wetter than average, and slightly sunnier than average.

The mean temperature this December was approximately 7.3 C making this the warmest December at Armagh for eight years, that is, since the very warm December 2015 (7.8 C), and the tenth warmest December at Armagh on record.

December 2023 was 2.7 C warmer than the 225-year (1796-2020) long-term December average at Armagh (4.64 C) and
2.1 C warmer than the most recent (1991-2020) 30-year average (5.23 C).

Except for December 2022 and July 2023, each month since June 2021 has been warmer than the month’s corresponding most recent (1991-2020) 30-year average. A year ago, this led to a record breaking 2022 mean
annual temperature (10.8 C).

This year, the mean annual temperature for 2023 (11.1 C) surpassed the previous record by a large margin. The six warmest calendar years at Armagh are now 2023 (11.1 C), 2022 (10.8 C), 2007 (10.6 C), 2021 and 2006 (both 10.5 C), and 1949 (10.4 C). That temperature records are now being made with increasing frequency is a strong signature of a changing climate.

The three highest maximum air temperatures this December, notionally the three warmest meteorological days (representing a 24-hour period starting at 09:00 GMT), were 13.0 C, followed by 12.8 C and 12.4 C.

These highest maximum temperatures were respectively attributed to the 23rd, 17th, and 26th December, though in each case the maximum daily temperature in fact occurred the following morning before 09:00 GMT, that is, during the mornings of the 24th, 18th, 27th. Such discrepancies in the date when a meteorological day’s maximum
temperature occurs happen on average nearly a quarter of the time in December at Armagh.

The three lowest maximum air temperatures, notionally the three coolest days, were 3.6 C, 3.7 C, and 5.0 C, which occurred respectively during the afternoons of the 3rd, 2nd and 1st of December. Taking the 31 December days together, the monthly average of the daily maxima was approximately 9.7 C, the equal seventh warmest such result (shared with 1953, 1942, and 1862) on record at Armagh.

The highest minimum air temperature, notionally the warmest night, was 10.7 C attributed to the 18th, though it in fact occurred shortly after the 09:00 GMT time of readings on the 17th. This was the highest minimum December temperature at Armagh for eight years, that is, since 11.1 C was recorded on both the 2nd and 17th of December 2015. The second and third highest minimum air temperatures this December were both 9.9 C, conventionally attributed to the 17th though in fact these temperature minima occurred around 09:00 GMT on the 16th and 23rd. Such discrepancies in the date of a meteorological day’s minimum temperature happen on average roughly half the time during December at Armagh.

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

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