MAY 2026 WARMER, DRIER, AND SLIGHTLY SUNNIER THAN AVERAGE. FOURTH WARMEST SPRING ON RECORD, DRIER AND SUNNIER THAN AVERAGE
Armagh Observatory, 4th June 2026: Armagh Observatory reports that May 2026 was warmer, drier, and slightly sunnier than average. Taking March, April, and May together, the meteorological spring was also drier and sunnier than average, and the fourth warmest spring on record at Armagh.
With an average temperature of 12.8 C, this May was approximately 1.4 C warmer than the corresponding most recent (1991-2020) 30-year average at Armagh (11.4 C) and 2.2 C warmer than the 225-year (1796-2020) long-term average (10.6 C). This May was the equal twelfth warmest May on record at Armagh, continuing a warming trend in which eight of the last ten Mays at Armagh have now been warmer than the most recent 30-year average.
A monthly average can often hide large variations. This May, more than half the month (the 3rd to the 18th) was cooler than average, but the cool start was more than made up by a very warm spell around the end of the month beginning on the 19th. Each of the six days from the 24th to the 29th reached maximum air temperatures greater than 5 degrees Celsius warmer than the most recent (1991-2020) 30-year average of the daily temperature maxima for May at Armagh (15.8 C). The highest temperature (26.3 C) occurred on Monday the 25th, the Spring Bank Holiday. This was the highest May temperature ever recorded at Armagh, though only marginally warmer than the previous record (26.2 C) set 37 years ago on 23rd May 1989.
Unlike parts of England and Wales, there was no heatwave in Northern Ireland, nor were any previous record May temperatures broken by a significant margin. According to the UK Met Office, a heatwave is only said to occur in Northern Ireland when the maximum air temperature meets or exceeds 25.0 C on at least three consecutive days. According to this definition, there has never been a May heatwave at Armagh.
230 Years of Weather Recording 14 July 2025 Armagh Observatory and Planetarium Armagh
CREDIT: LiamMcArdle.com
This May, the three warmest days or highest maximum air temperatures at Armagh were 26.3 C on the 25th, followed by 23.8 C on the 27th, and 23.6 C on the 24th. Similarly, the warmest night, or highest minimum air temperature, was 13.3 C on the 28th, followed by 13.1 C on the 24th, and 13.0 C on both the 22nd and 29th.
By contrast, the three coolest days or lowest maximum air temperatures were 12.4 C on the 3rd, followed by 13.4 C on the 9th, and 13.7 C on the 5th. The coolest nights, or lowest minimum air temperatures, were 0.2 C on the 6th, followed by 0.3 C on the 10th, and 3.2 C on the 9th.
Although there were therefore no air frosts this month there were 14 ground frosts, that is, nights when the grass-minimum temperature fell to less than or equal to zero Celsius. Among these the coldest were -7.3 C on the 10th, followed by -5.1 C on the 6th, and -3.2 C on the 9th.
230 Years of Weather Recording 14 July 2025 Armagh Observatory and Planetarium Armagh
CREDIT: LiamMcArdle.com
Total precipitation was 40.0 mm including 4 trace values, that is, 39.8 mm if trace values are ignored. This is approximately 68.3% of the 183-year (1838-2020) long-term average May precipitation at Armagh (58.6 mm) and 68.7% of the most recent (1991-2020) 30-year average (58.2 mm). May 2026 therefore continues a pattern in which now ten of the last fifteen Mays have been drier than average. It is noteworthy that, despite recent warming, monthly rainfall at Armagh has changed very little on average over two hundred years.
The wettest day was the 19th with 9.2 mm of precipitation, followed by the 17th with 7.3 mm and the 18th with 4.9 mm, these three relatively wet days together supplying more than half the month’s total rainfall. There were 15 rain days this month, that is, days with greater than or equal to 0.2 mm of precipitation.
The observer noted partial rainbows on the morning and evening of the 13th, and thunder on the 17th. Swifts were recorded on the 1st and 27th, and swallows on the 14th, 18th, and 21st. The average atmospheric pressure recorded at 09:00 GMT and reduced to mean sea level each day was 1017 mbar, close to the most recent (1991-2020) 30-year average at Armagh (1016 mbar).
May 2026 recorded 184.5 hours of strong sunshine, approximately 4.6% more than the 140-year (1881-2020) long-term May average at Armagh (176.4 hours) and 3.2% more than the most recent (1991-2020) 30-year average (178.8 hours). The month was therefore only slightly sunnier than average.
The sunniest day was the 9th with 14.3 hours of strong sunshine, followed by the 27th with 12.8 hours, and the 24th with 12.2 hours. There were two sunless days this month, that is, days with zero hours of strong sunshine, which occurred on two successive days, namely the 2nd and 3rd. There were four dull days, that is, days with less than 0.5 hours of strong sunshine.
230 Years of Weather Recording 14 July 2025 Armagh Observatory and Planetarium Armagh
CREDIT: LiamMcArdle.com
Taking the three months March, April and May together, meteorological spring 2026 was warmer, sunnier, and drier than average. With an average temperature of 10.1 C, this was approximately 2.0 C warmer than the 225-year long-term (1796-2020) spring average at Armagh (8.1 C) and 1.1 C warmer than the most recent (1991-2020) 30-year average (9.0 C). This spring was the fourth warmest on record at Armagh, continuing a trend towards warmer-than-average springs at Armagh. Among the fifteen warmest springs at Armagh, ten have occurred in just the last twenty years.
Total spring precipitation was 147.6 mm, approximately 88% of the 183-year (1838-2020) long-term average spring precipitation at Armagh (167.0 mm) and 85% of the most recent (1991-2020) 30-year average (173.8 mm).
With each of the meteorological spring months (March, April, May) sunnier than average, spring 2026 was also sunnier than average with 501.5 hours of strong sunshine. This is approximately 18% more than the 140-year (1881-2020) long-term spring average at Armagh (424.4 hours) and 16% more than the most recent (1991-2020) 30-year average (431.6 hours), leading to this being the eighteenth sunniest spring on record at Armagh.
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
Emeritus Director of Armagh Observatory
Armagh Observatory and Planetarium
College Hill
Armagh
BT61 9DG
Tel: 028-3752-2928
E-mail: mark.bailey@armagh.ac.uk
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