RECORD-BREAKING AUGUST AT ARMAGH: DRIEST FOR 19 YEARS, WARMEST FOR 25 YEARS, AND SUNNIEST FOR 27 YEARS. SUMMER 2022 MUCH WARMER THAN AVERAGE, DRIEST FOR 27 YEARS, AND SLIGHTLY SUNNIER THAN AVERAGE.
Armagh Observatory reports that August 2022 was the driest at Armagh since August 2003, the warmest since August 1997, and the sunniest since August 1995. Taking the three months June, July, and August together, the meteorological summer was much warmer than average, the driest at Armagh since summer 1995, and slightly sunnier than average.
Total August precipitation was 24.9 mm (0.98 inches) including two trace values, that is, 24.8 mm if trace values are ignored. This is approximately 30% of the 183-year long-term (1838–2020) average August precipitation at Armagh (82.35 mm) and 32% of the most recent (1991–2020) 30-year average (78.62 mm). This August was much drier than average, the driest August at Armagh for 19 years, that is, since August 2003 (17.4 mm), and the seventh-driest August at Armagh since rainfall records began in 1838. There was measurable precipitation on 13 days including two trace values, but no very wet days.
The wettest day was the 1st with 6.8 mm (0.27 inches) of rainfall, followed by the 21st with 6.4 mm (0.25 inches) and the 25th with 3.7 mm (0.15 inches). These three days supplied more than two-thirds the total precipitation for the month.
Thunder was heard on the afternoon of the 14th, and around midday on the 6th a group of four peacock butterflies was noted near the entrance to the woodland walk in the Observatory demesne.
This August, like August 2021, was dominated by high pressure. The mean monthly
pressure reduced to mean sea level was approximately 1018 mbar, slightly more than the average last year (1016 mbar).
The daily-averaged mean monthly temperature, approximately 17.0 degrees Celsius (62.5 Fahrenheit), was much warmer than any recent August at Armagh, 2.34 C above the 225-year long-term (1796–2020) average August temperature at Armagh (14.63 C) and 1.48 C above the most recent (1991–2020) 30-year August average (15.48 C). This was the warmest August at Armagh for 25 years, that is, since August 1997 (mean temperature 17.1 C).
In this context it is interesting to note that average August temperatures at Armagh have increased significantly over the last 40 years. Whereas the (1961–1990) 30-year average was 14.82 C, the most recent (1991–2020) 30-year average was 15.48 C, an increase of 0.66 C in 30 years.
August 2022 was also remarkable for a run of very warm temperatures during the second week of the month. The UK Meteorological Office defines a heat wave in Northern Ireland to be any period of at least three consecutive days when the maximum temperature meets or exceeds 25.0 C (77 F), a condition that was met for a five-day period beginning on August 9th and lasting through to the 13th.
August heatwaves are relatively uncommon, with just ten examples (including 2022) in the 178 years since daily maximum and minimum temperatures began at the Observatory in 1844. Long-duration heatwaves lasting five days or more are less frequent, with only five cases in the Observatory’s long-term temperature records, the most recent being August 1995. The August 2022 heatwave was therefore the longest such event at Armagh for 27 years.
The hottest day (highest maximum temperature) was 29.0 C on the 13th, coming at the end of the five-day heatwave. This was the second-hottest day of the year (after 31.2 C recorded on 18 July 2022) and the equal-second warmest August day at Armagh since records began in 1844, shared with 4th August 1856, and surpassed only by 29.4 C on 20 August 1995. The monthly mean maximum temperature (22.0 C) was also unusually high, the fourth-warmest average maximum temperature for August at Armagh since records began.
The second, third and fourth warmest days were 28.3 C on the 11th, 28.2 C on the 12th, and 26.9 C on the 10th. The five warmest August days recorded at Armagh are now 29.4 C (20 August 1995), 29.0 C (4 August 1856 and 13 August 2022), and 28.9 C (17 August1995 and 3 August 1975).
An unexpected incident resulting from the five-day August heatwave happened close to the Planetarium on the 13th. Here, it was noticed that with the exceptional very dry, hot conditions the bark-mulch on the herbaceous bed in front of the Planetarium had begun to smoulder. Prompt attendance by the fire service avoided what might have become a more serious event.
The coolest day (lowest maximum temperature) was 17.9 C on the 26th, followed by 18.2 C on the 20th and 18.5 C on the 17th. The highest minimum temperature, which is usually the warmest night was 17.2 C on the 2nd, although the actual minimum occurred on the afternoon of the 1st rather than during the night of the 1st/2nd. This was the highest August minimum temperature for 16 years, that is, since a highest minimum of 17.7 C was recorded on 6 August 2006.
The coldest night (lowest minimum temperature) was 8.3 C in the small hours of the 27th followed by 9.0 C on the 8th. There were no ground frosts this month, the two lowest grass-minimum temperatures being 2.0 C on the 1st and 2.1 C on the 27th.
This August was remarkable for its long periods of strong sunshine. In contrast to the
previous August 2021, which was exceptionally dull, August 2022 supplied a total of 213.1 hours of strong sunshine, approximately 160% of the 183-year long-term (1881–2020) average at Armagh (133 hours) and 150% of the most recent (1991–2020) 30-year average (141 hours). This was the sunniest August at Armagh for 27 years, that is, since the exceptionally sunny August 1995 (242.7 hours), and the fifth-sunniest August on record at Armagh since the advent of daily sunshine records in 1880.
The three sunniest days, namely 14.2 hours on both the 10th and 11th, and 14.0 hours on the 9th, all occurred during the five-day heatwave. Taking the three summer months June, July and August together the meteorological summer was much warmer than average, the driest for 27 years and slightly sunnier than average.
With an average daily temperature of 16.1 C (61.0 F) the mean summer temperature was approximately 1.8 C warmer than the 225-year long-term (1796–2020) average summer temperature at Armagh (14.3 C) and 1.0 C warmer than the most recent (1991–2020) 30-year average (15.1 C). Summer 2022 at Armagh was only 0.1 C cooler than last year’s exceptionally warm summer (16.2 C) and the ninth-warmest summer at Armagh since daily temperature records began around 1795.
Summer 2022 was also very dry. Each summer month was drier than average, and August exceptionally so, leading to a total summer rainfall of just 104.2 mm (4.1 inches) including 14 trace values, or 103.5 mm if trace values are ignored. This is approximately 47% of the 183-year long-term (1838–2020) summer average at Armagh (219.4 mm) and 49% of the most recent (1991–2020) 30-year average (210.5 mm). This was the seventh-driest summer at Armagh since daily rainfall records began in 1838 and the driest summer at Armagh for 27 years, that is, since summer 1995 (80.0 mm). Rainfall averages at Armagh fluctuate significantly from year to year but show no significant trends versus time, so spells of dry weather have always been balanced by wetter periods and this will presumably continue.
Despite June and July being duller than average (and July exceptionally so) the very sunny August brought the total number of hours of strong summer sunshine to 442.1 hours. This is approximately 4% more than the 140-year long-term (1880–2020) average (427 hours) at Armagh and 5% more than the most recent (1991–2020) 30-year average (420 hours). This was the sunniest summer at Armagh for 6 years, that is, since summer 2018 (478.2 hours of strong sunshine).
FOR FURTHER INFORMATION PLEASE CONTACT:
Mark Bailey at the Armagh Observatory, College Hill, Armagh, BT61 9DG.