April 2024 Weather Round-Up

APRIL WARMER, WETTER, AND DULLER THAN AVERAGE

Armagh Observatory, 3rd May 2024:

Armagh Observatory reports that April 2024 at Armagh was warmer, wetter, and duller than average. The mean temperature, approximately 9.2 degrees Celsius, was 1.3 C warmer than the 225-year long-term (1796–2020) April average at Armagh (7.92 C), and 0.4 C warmer than the most recent (1991–2020) 30-year average (8.80 C). Total rainfall was 61.2 mm including 4 trace values. This was 16% more than the 183-year long-term average at Armagh (52.75 mm), and 9.5% more than the most recent (1991–2020) 30-year average (55.9 mm). The total number of hours of strong sunshine (127.5 hours) was approximately 85% of the most recent (1991–2020) 30-year average (149.9 hours).

A sign of this year’s warmer-than-average April is that the date of the first swallow seen at the Observatory this year was the 16th, with more swallows recorded on the 25th. In recent years the date of the first swallow at the Observatory has been around the end of April or early May.

The highest maximum air temperature, or warmest day, was 19.2 C on the 21st, followed by 16.8 C on the 11th, and 16.6 C on the 5th. The lowest maximum air temperature, usually the coolest day, was 9.4 C on the 1st, followed by 9.6 C on the 17th, and 10.0 C on the 8th.

The highest minimum air temperature, usually the warmest night, was a very mild 12.2 C on the 12th. This was the warmest April night at Armagh for 13 years, that is, since the night of the 6th of April 2011 (12.6 C). It was also the fifth warmest April night at Armagh since daily records of maximum and minimum temperatures began around 1844. This very mild April night was followed by a minimum temperature of 10.4 C attributed to the 6th, although occurring shortly before midnight on the 5th. This was followed in turn by 9.3 C attributed to the 11th, although this highest minimum temperature actually occurred around the time of observations (09:00 GMT) on the 10th. The lowest minimum air temperature, usually the coolest night, was -0.9 C on the 28th, followed by -0.8 C on the 27th, and 1.7 C on the 20th.

There were several quite sharp ground frosts among the 14 nights with recorded grass minimum temperatures less than or equal to zero Celsius, the coolest of which were -7.8 C on the 27th, -7.7 C on the 28th, and -4.9 C on the 25th. There were only two days, the 28th and 27th, with night-time air frosts.

Storm Kathleen, the 14th named storm to have significantly affected one or another part of the UK and Ireland during the present 2023/2024 storm season, brought strong winds on the 6th, sometimes approaching near gale force. This storm was also associated with an unusually low atmospheric pressure for April, recorded at Armagh as approximately 979.4 mbar reduced to mean sea level. This was the lowest April atmospheric pressure at Armagh for 25 years, that is, since 975.4 mbar occurred on the 21st of April 1999. Total precipitation was 61.20 mm including 4 trace values, that is, 61.0 mm if trace values are ignored. The wettest day was the 14th with a total rainfall of 12.2 mm (0.48 inches), followed by the 8th with 9.5 mm, and the 4th with 8.3 mm. A double rainbow with a supernumerary bow below was noted on the afternoon of the 6th. This too was associated with the passage of Storm Kathleen. Showers with hail were recorded around the middle of the month on the 13th, 15th, and 16th.

The 127.5 hours of strong sunshine represented 87.6% of the 140-year (1881–2020) long-term April average at Armagh (145.54 hours) and 85.1% the most recent (1991–2020) 30-year average (149.87 hours). This April was therefore duller than average, the dullest April at Armagh since April 2019 (108.5 hours of strong sunshine). The sunniest day was the
20th with 12.2 hours of strong sunshine, followed by the 7th (10.7 hours) and the 16th (9.7 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/.