Armagh Observatory, 6th April 2024: Armagh Observatory reports that March was much wetter, rather warmer, and duller than average at Armagh.

For the second year in a row March was unseasonably wet. March is usually one of the four drier months of the year at Armagh, that is, February, March, April and May, but this March saw 107.95 mm (4.25 inches) of precipitation including three trace values, or 107.8 mm if trace values are ignored. This is nearly 95% more than the 183-year long-term (1838– 2020) average March precipitation at Armagh (55.7 mm) and 82% more than the most recent (1991–2020) 30-year average (59.7 mm).

March 2024 is now the sixth wettest March on record at Armagh, that is, since daily rainfall readings began at the Observatory in 1838. There is some evidence that March has become slightly wetter at Armagh than in years past, and that occasional very wet March days have become more frequent.

The wettest day was the 19th with 19.4 mm (0.76 inches) of rainfall, followed by 12.8 mm on the 13th and 10.1 mm on the 26th.
Snow fell for a while during the afternoon of the 28th. This was associated with the passage of Storm Nelson, which had been named by the Spanish Meteorological Agency, Aemet, and was the 13th named storm to have affected parts of the UK and Ireland to some degree during this current 2023/2024 storm season. Whereas Storm Nelson battered Wales and the south of England that afternoon, it produced few noticeable effects in Northern Ireland except two days of unusually low atmospheric pressure for March.

Observations at 09:00 GMT on the 27th recorded an atmospheric pressure at Armagh of approximately 970.8 mbar reduced to mean sea level, but those on the 28th saw 970.4 mbar. This was the lowest March atmospheric pressure at Armagh for 16 years, that is, since 10th March 2008 (959.4 mbar reduced to mean sea level).

The weather this month was dominated by lower-than-average pressure, providing a mean monthly average of approximately 1002 mbar reduced to mean sea level. This value, more than 10 mbar below the 175-year long-term March average at Armagh, was the lowest monthly average March pressure at Armagh for 43 years, that is, since March 1981 (999 mbar). It was also the second or third lowest mean March pressure at Armagh since calibrated records began around 1850.
Formally, the half-dozen lowest mean March pressures at Armagh are now 1981 (999.1 mbar), 1947 (1001.6 mbar), 2024 (1002.0 mbar), 1876 (1002.3 mbar), 1903 (1002.4 mbar), and 1912 (1002.5 mbar), though instrumental and other uncertainties are probably around 0.5 mbar.

Rainbows were seen on the afternoons of the 22nd and 29th, and showers with hail on the 22nd, 27th, 29th, and 30th. Those on the afternoon of the 30th included larger hailstones with diameters in the approximate range 5 to 10 mm.

The average temperature this month, that is, the mean of the daily maxima and minima, was 7.47 degrees Celsius (45.5 F), nearly 1.7 C warmer than the 225-year long-term (1796–2020) March average at Armagh of 5.82 C and approximately 0.7 C warmer than the most recent (1991–2020) 30-year average (6.75 C). Five of the last six years at Armagh have now had average March temperatures greater than 7.0 C.

The highest daily maximum air temperature was 14.5 C, seen on the 17th and 31st, followed by 13.6 C on the 30th. The 17th and 31st were the equal warmest days of the year, that is, since 23rd January 2024 (14.2 C). The 17th was also the mildest St Patrick’s Day at Armagh for 19 years, that is, since the dull but mild 17th March 2005 (maximum temperature 15.2 C). The lowest maximum air temperature or coolest day was 6.4 C on the 1st, followed by 6.7 C on the 26th and 6.8 C on the 10th.

The highest minimum air temperature, usually the warmest night, was 8.5 C on the 19th followed by 7.4 C on the 13th. The two lowest minimum air temperatures, or coolest nights, were -1.9 C on the 29th followed by -1.0 C on the 16th. These were the only two nights this month with night-time air frost.

There were 14 nights with ground frost (minimum grass temperatures less than or equal to zero Celsius) of which the three coldest were -6.1 C on the 16th, followed by -5.0 C on both the 2nd and 29th.

With a total of 92.9 hours of strong sunshine, this March was slightly duller than average, with approximately 91% of the 140-year long-term (1881–2020) March average (102.4 hours) and 90% of the most recent (1991–2020) 30-year average (103.0 hours). The sunniest day was the 30th with 9.8 hours of strong sunshine, followed by the 22nd with 8.5 hours and the 7th with 8.0 hours.

 

These data refer to observations at Armagh Observatory, which has been recording the weather at Armagh since 1795.
FOR FURTHER INFORMATION PLEASE CONTACT: Mark Bailey at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; mark.bailey@armagh.ac.uk; URL: http://climate.arm.ac.uk/


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